The forerunner of modern collective residence in Hankou: the study on Panoffs’ Mansion

ABSTRACT Collective residence is the choice of urban residents for residential buildings in the context of urban intensification and population densification in modern times. Starting from the modern collective residence in the former concession area of Hankou, this paper, with the focus on Panoffs’ Mansion in the former Russian Concession, through field investigation and literature, original spatial pattern was deduced according to the current situation. Through the diagram analysis of its spatial sequence and organization, and comparative analysis with other collective residence in Hankou, to discuss the similarities and differences between the mansion and other modern Hankou collective residence in form, layout, internal space pattern and living mode. The urban texture of concession completely different form Hankou Old Town, but regional elements are integrated. Panoffs’ Mansion has these common characteristics. Moreover, its volume occupies a single block, and it is the earliest unit residence in Hankou. Panoffs’ Mansion is the earliest practice of unit housing in Hankou, which plays a leading role in modern housing in Hankou. The study of its spatial organization and architectural form is of great significance to the study of modern housing in Hankou concession. GRAPHICAL ABSTRACT


Introduction
As the largest high-grade apartment in Hankou 1 during the late Qing Dynasty and the early Republic of China, Panoffs' Mansion is located in the former Russian Concession of Jiang'an District, Wuhan, China. It, as a pioneer of apartment building in Wuhan, serves as the earliest architectural practice of collective residence 2 in Hankou. Also, it is a typical example with the characteristics of modern collective residence in the former Concession of Hankou. Since its completion, Panoffs' Mansion has undergone the return of the Hankou concession and the founding of the People's Republic of China. The residents changed several times. Nowadays, they have moved out, and the related renovation tasks of this building are on the agenda.
Panoffs' Mansion is a luxury apartment invested and constructed by the Russian tea merchant J. K. Panoff. 3 It was built in 1901 and is located at No. 45-56 Poyang Street in the former Russian Concession of Hankou. There is no exact information on its designer. According to Wuhan Cultural & Historical Material Some sources recorded that the apartment was designed by Hemmings & Berkley, while others say it was designed by a Russian architect. But from the Real Estate Bureau, the information about the designer: unknown (Fang 2009). The construction of Panoffs' Mansion was carried out in two phases. The side of Lanling Road was built first, which was larger, so it was called "Larger Bagong". The side of Lihuangpi Road was built later, which was called "Smaller Bagong", because of its smaller size and building area." (Lan 2003). Larger Bagong was completed in 1910 and Smaller Bagong was completed no later than 1912 4 ( Figure 1). The word "Bagong" comes from the Chinese pronunciation of Panoff, "Ba" is the abbreviation for Panoff in Chinese, and "gong" means a respectful title for a person of status and prestige in Chinese, so Panoff's Mansion is referred to as Bagong House in Hankou.
Research on the Hankou modern housings mostly focus on Li-fen residence. 5 Collective residence usually serves as a component of Hankou buildings (Li, Xu, and Wu 2000;Chen 2017). Li expounded the characteristics of the Li-fen residence in modern Wuhan from development process, plane layout, structure, decoration and detail, and living form. In this paper, the object is collective residence in Hankou and focuses on a representative building. The volume organization, living mode and architectural form are mainly analyzed. By means of literature research and image analysis, Chen compares the changes of Hankou's modern social formation (politics, economy, people, events, daily life, etc.) and its influence on the living form, so as to obtain the "historical scene" in which people lived at that time. This paper uses the method of literature research and image analysis to deduce the living pattern of Panoff's Mansion in connection with the social formation background. The research on single residential buildings mainly focuses on the industry of Jardine Matheson, a British firm (Zhou 2017). Zhou reveals the influence of British Victorian residence on the residence of the firm in Hankou at the same time. Panoff's Mansion was also influenced by contemporary Russian residential architecture. The related literature of Panoffs' Mansion focuses on its historical evolution and decorative art (Zhang 2016). Most of the written information about Panoff's Mansion comes from local cultural magazines or newspapers, documenting its history from a humanistic perspective (Hu 1997(Hu , 2000Fang 2009;Jiang 2015). The Resource Library of Southeast University records an article on Panoff's 3 J·K·Panoff, as a Russian nobleman, was the owner of the Panoffs' Mansion. In 1869, he came to Hankou and served as the manager of Xintai Company. In 1874, he founded Fuchang Company and engaged in tea trade. He once served as the Russian consul in Hankou. 4 There is no detailed record of when was built. But it was built after Larger Bagong, and Panoffs' Mansion was resold in 1912, so it is estimated that Smaller Bagong was built no later than 1912. 5 Li-fen residence is a kind of multi-row house commonly built in Wuhan from the end of the 19th century to the first half of the 20th century, which is one of the main types of the residential building in modern Wuhan.
Mansion published by Yishi Newspaper on 9 March 1947, which introduced the living conditions of the residents and described the complex living population and crowded living environment at that time (Zhao 1946). There is a lack of systematic research on modern collective residence in Hankou as well as its spatial organization and the living mode of single buildings.
According to the systematic research on existing collective residence in Hankou former concession as well as a series of field survey and mapping of Panoffs' Mansion, efforts are made to comb out the common features of collective residence in modern Hankou, in combination with some historical literature. besides, with the focus on Panoffs' Mansion, efforts are made to distinguish its difference from other collective residence and deeply explore its spatial organization, volume and form.

The historical era of Hankou Concession
In 1861, Hankou opened its port. The concessions of Britain, France, Germany, Japan, Russia were demarcated here. Businessmen and missionaries from various countries settled here successively. The modern collective residence in the former concession of Hankou was built to meet the residential demand of colonists. The concession of the five countries is located in the north of the Old Town of Hankou, along the Yangtze River, with a total area of about 1.87 k㎡ (Liu 2006). The British Concession was the first to establish, so it is the closest to the Old Town. The Russian Concession was established in 1896, covering an area of about 414 acres, accounted in the unit of Qing Dynasty including today's Hezuo Road to Huangxing Road, Dongting Street to Chezhan Road, located in the north of the British Concession (Hu 2003). Before that, this area was the racecourse of British, but after the establishment of Russian Concession, the racecourse was moved to the north of the concession area (Figure 2,3,4).
From the second half of the 19th century to the beginning of the 20th century, China was still in the Qing Dynasty, a feudal country with foreign concessions. Many European countries set up concessions in major cities in China, including Shanghai, Guangzhou, Wuhan and Tianjin. Wuhan includes three towns, Hankou, Wuchang and Hanyang, where the water system is developed and the urban pattern is dominated by the freestyle road network adapted to local conditions. The Old Town of Hankou is located at the junction of the Yangtze River and the Han River, and the concession area is located along the Yangtze River on the north side of the Old Town. At that time, Europe experienced rapid urbanization brought by the Industrial Revolution. Modern collective residence, as a kind of residential buildings with the development of capital economy and urbanization, gradually become the mainstream of urban residential form. Its spatial organization and living mode have significant difference from traditional housings, including hotel apartment, dormitory, commerce-residence building, etc. The colonists introduced modern residential buildings into China, which provided a precedent for the development of Chinese urban houses, and greatly influenced the evolution of urban housing space from traditional to modern in China. On the one hand, modern collective residence in the former concession of Hankou inherited the architectural style and urban texture of occidental cities; on the other hand, it reflected the transformation of the living mode and lifestyle of modern urban residents brought about by the urbanization process and promoted by capitalist economic development. Hankou was pushed onto the road of modernization by colonial trade which objectively promoted the development of economy and urbanization of the city. According the material in The Second Historical Archives of China, "Located at the junction of the Yangtze River and Han River, Hankou is the hub of the Yangtze River waterway, so it had been one of the famous towns in China before the ban on maritime trade was abolished. Since The Treaty of Tianjin set Hankou as a commercial port, Britain, Russia, Germany, France and Japan successively established their concessions there. Later, Beijing-Hankou railway and Guangzhou-Hankou railway were built; as a consequence, Hankou became the largest metropolis in central China with developed industry and commerce as well as booming population." After entering the 20th century, with the gradual maturation of commercial trade and residential environment, the population of foreign nationals in Hankou increased rapidly (Zhu 2014), which promoted the construction of concession. It was not limited to their own nationals living or doing business in the concessions, which Chinese can also settle in. The colonialists set up factories and firms in the concession. Many dormitories or apartments were built by the capitalists for the residential demand of the employees, which were usually located around their workplace for commuting. Therefore, collective residence in the former concession of Hankou is mainly composed of staff dormitories, such as Jardine Apartment, 6 Racine & Cie.S.A. Apartment 7 and Mitsubishi Dormitory. 8 With the increase of colonial population, churches and affiliated apartments or hotels for clergy and parishioners were founded in the concession, which was likewise a form of collective residence. This kind of temporary residence was usually adjacent to churches, such as Hankou Lutheran Church 9 and St. Lazarus Church. Cross-concession residence and population growth created a market for commercial apartments. As the result, there were commercial apartments invested by capitalists for rent or sale, which were usually relatively high-grade and decorated luxurious, such as Panoffs' Mansion, Delin apartment, 10 and so on.

The economic activities involved by Panoff
In 1874, J.K. Panoff and his partner founded the Fuchang Brick Tea Factory. In the 1890s, the factory became the largest brick tea manufacturer in the Russian Concession. Panoff was the former Russian consul in Hankou in 1902, and was locally honored as "Lord Panoff". It can be seen that Panoff's social prestige and capital strength were second to none in the Russian Concession at that time. Mechanic Chere Panoff 11 designed the steam tea machine, greatly reducing the cost of production and accelerating the capital accumulation of the factory. In addition, according to Wuhan Cultural & Historical Material, Panoff held the "Complete Library in the Four Branches of Literature" looted during the invasion of China by the Eight-power Allied forces, which was redeemed by Yuan Shikai for a large sum of money in 1901. Later, Panoff began to invest in the field of real estate. Since then, he turned to the real estate business, investing in many buildings in the Russian and British concession with the help of the of the Imperial Russia forces. He became the largest real estate owner in the concession (Hu 1997). After October Revolution, the Russian-owned tea factories in the concession were closed or resold, and Panoff left Hankou in 1921.

The construction process of Panoffs' Mansion
According to Wuhan Cultural & Historical Data, real estate occupied by Shunfeng, Xintai and Fuchang three brick tea factory accounts for more than half of the area of Russian Concession. Among them, Fuchang was the greatest, because the land of racecourse had been purchased by Panoff before the concession set up (Hu 2000) (Figure 2). The land included the area around Dongting Street and Lanling Road, Li Huangpi Road, Luojiashan Road. In 1901, Panoff invested 150,000 taels of silver to build the first multi-storey apartment in Hankou in the triangular site enclosed by Dongting Street, Poyang Street and Lanling Road, 12 which was later called "Panoffs' Mansion" (Zhang 2013).
Panoffs' Mansion is a masonry of wood structure, with 3 floors above ground and 1 floor underground when first built. It is a fusion of Russian ethnic characteristics and romantic elements, which is the prevailing classical revival style in Europe at that time. The whole building is in Russian style and triangular in shape. The hall on the third floor at the sharp corner is shaped like a monk's hat; as a result, the building is commonly known as the "Russian head tip" (Hu 2000). The whole building is in Russian style and triangular in shape. The hall on the third floor at the sharp corner is shaped like a monk's hat; as a result, the building is commonly known as the "Russian head tip". (Wu & Hu & Wang & Cheng & Chen 2009) After the founding of The People's Republic of China in 1949, Panoffs' Mansion was nationalized and allocated to bank employees as public housing. Due to the shortage of residential space, an additional storey was added to the top of the building in 1964. The ground floor of the building is 4.3 meters high, the second and third floors are 3.8 meters high, and the additional fourth floor is 3 meter high. The red plain brick wall is still used in the addition part of Smaller Bagong, and the facade basically inherited the style of the original building, while the brick wall is brushed with cement mortar outside the addition part of the Larger Bagong, which is not unified with the original style. The result is the building volume of four-storey and the facade of material split we see today (Figure 5,6). Because of the shortage of living space, all the interior balconies were enclosed as interior space; some rooms were even divided into two rooms; some residents, who took advantage of the height, build mezzanine in order to expand their space. But even before the additional floor, Panoff's Mansion was already overcrowded. An article on Panoff's Mansion published in the Yishi Newspaper in 1947 describes the complex residents and cramped living conditions of the time: "Every floor, every room, every corner, even the hole in the ground beneath the building was full of people . . . Maybe two or three thousand residents." (Zhao 1946) For this reason, the partition wall of the room possibly had existed before the additional floor, and this state of affairs has persisted to this day (Figure 7, 8).
These alterations have destroyed the spatial organization inside the Panoff's Mansion, and the current situation presents a chaotic and fragmented state. The research on the characteristics of spatial organization in this paper will be based on the restored original plane.

Derivative of modern collective residence in Hankou
Efforts are made to investigate the existing modern collective residence in the former concession of Hankou, which is listed in the historical protection buildings of Wuhan City. The collective residence listed in the table are located in the original concessions of five countries (Britain, France, Germany, Japan and Russia), which is part of the representative wellpreserved (Table 1). The table shows the concession they locate in, the age, the style, the planar contour and the residential mode. Their form is heavily influenced by the architectural style of the country they belong to, and most of them have obvious unitary appearance and are usually composed of 2-3 stories. They are built close to the road boundary and attach importance to the design of facades along the road. They are mainly apartments and dormitories, one of which is a hotel, and a few ground floors have commercial and office. It can be seen that the planar contour of Panoff's Mansion is unique among them, and it is also the earliest commercial residence in Hankou.

Urban texture of architecture conforming to the boundary of block
Different from the freestyle road network naturally formed in Hankou Old Town during its long-term historical evolution, the urban pattern of the concession area is a grid formed by planning, which is an urban planning model applicable to any newly developed area and easy to copy (Zhu 2014). Collective residence in concession of Hankou has two types of planar contour: point type and slab type. 13 The collective buildings in slab type are mostly constructed along the road boundary, paying attention to the composition of the facade along the street, especially the treatment of the relationship between the architectural form at the corner and the road. For example, Hankou Lutheran Church adopts a curved planar contour at the corner; Mitsubishi Corporation Staff Dormitory makes one unit at the corner three floors high, while the rest has only two floors, shaping the urban space through the landmark structures at the corner ( Table 1).
The former concession of Hankou imitates the spatial form of traditional occidental cities, but most area do not strictly control the consistency of building exterior and road boundary as the European cities do. Hankou was opened as the port. The evolution of urban morphology of Hankou is a kind of mutation and integration from inner to outer, which made the urban pattern transform gradually from along the Han River to along the Yangtze River. And street space layout is transforming from "building is divided by street" to "street is divided by building", which is the origin of modern Wuhan as a riverside city (He and Dong 2004). With the exception of a few blocks that form in inner courtyards like occidental blocks, for example, Panoffs' Mansion, most blocks are further divided into smaller streets and lanes which were known as "Li-Fen" in Hankou. In the chessboardtyped block (street passageway), the space developed inward is still embodied by the traditional "Li Fang" system (with the workshop door, if possible), by which "characteristics of linear space" (major lane and minor lane) is formed. This linear space is different from the exterior space formed by housing in the form of dot and block in occidental blocks (Chen 2017). This smaller scale of inward development inside the blocks occurs in the larger scale of the grid type of urban planning. In fact, although the planning of the concession was quite different from the form of the Old Town of Hankou, with the intervention of Chinese capital in the concession, they merged into a new form. This urban form has not only been preserved to this day, but also influenced the planning of the then undeveloped area on the north side of Hankou Old Town.

Living mode adapting to foreign residents
The collective houses in the former concession of Hankou are mostly apartment, for example, Jardine  13 The length to width ratio of the architecture contour of point type is less than 2, while the ratio of the slab type is greater than 2. Apartment. The unit usually contains a number rooms, including kitchen, bathroom, and living room in more upscale apartments, such as Jardine Executive House and Panoffs' Mansion. Such a division has been completely similar to the spatial organization of modern collective residence. When the concession in Hankou was established, Europe was during the process of the Second Industrial Revolution, when the cities were faced with a myriad of new factories, population explosion, and land tension, and the rapid development of capitalist economy subverted the traditional life and living mode. People originally engaged in agricultural production turned to industrial production or commercial management, and the living environment got rid of the restriction of arable land; as a result, the organization of living space could be more intensive. Collective residence gradually emerged and became the mainstream of urban living, which was still adopted by occidental colonists in the concessions. Most of the collective houses in the former concession of Hankou are dormitories or apartments built by foreign firms for their staff. The majority of these residents are foreigners who came to work in China overseas, usually alone or with their partners and children. Therefore, the population of single families greatly reduced compared with that of traditional families. The living mode of collective residence with multiple units in a single building was more suitable for their needs. The interior decoration and spatial layout of these dormitories or apartments were superior to the civilian houses in Hankou at that time.

Architecture style of classics and colonialism
Modern collective residence in the former concession of Hankou was residential architecture built under the volition of occidental colonists. The architecture is mainly in the classical revival style prevailing in Europe at that time and in the colonial style 14 with corridor. The collective houses of the classical revival style usually present repetition of motif in terms of facade composition, emphasizing proportion and symmetry, such as the facade of Jardine Apartment along Poyang Street. The interior space also strives for a symmetrical layout, adopting elements such as classical columns and arches. The colonial-style building features an exterior porch, which could be exactly a balcony or corridor connecting units. The colonial style is an architectural form created by colonizers in Southeast Asia to adapt to the local hot and humid climate. With the migration, it was introduced to the concessions of major cities in China, which was the occidental architectural style that Chinese firstly came into contact with (Liu 2013 In addition, the modern collective houses in the former concession of Hankou incorporate the architectural characteristics of European ethnic styles. For Panoffs' Mansion, there is a Russian-style dome at the corner and cantilevered balconies on the façade along    street. Jardine Executive House is an apartment built by Jardine Matheson for its senior officer, which is concise in form, adopting the gabled roof common in British dwellings, with the facade differentiated by materials and the gabled roof commonly used in British dwellings.

Collective house with inner courtyard
The majority of collective houses in the former concession of Hankou are slab-type or point-type. The feature of Panoffs' Mansion is that the whole block is occupied by it and the huge building volume is organized through the inner courtyard ( Figure 9). The plane form is more similar to the spatial form of European city blocks: the blocks are shaped by the building volume, and the facades along the street are controlled by strict regulatory plan, forming a uniform street interface, while the interior of the block is enclosed by a physical volume with an inner courtyard, often with additional buildings connecting the two sides to augment the building area ( Figure 10).

Huge volume of the building
The volume of Panoffs' Mansion is second to none in the former concession of Hankou, with a land area of 3998㎡ and a base area of 2368 ㎡, with a building density of 59.4% and a building area of about 9423㎡. During the same period, a single plot unit in the Russian Concession is about 2000 ㎡, and most blocks are divided into 5 to 10 plot units, except for industrial estates. Panoffs' Mansion is the only non-industrial building that occupies a single block. The road network of the concession shows that the triangular block where Panoffs' Mansion is located is the result of the connection between the three main roads parallel to the Yangtze River in the French Concession and the four main roads parallel to the river in the British Concession ( Figure 11). Zhu from Tsinghua University explained that the area of the Russian Concession used to be the racecourse of British. In order to keep away from the racecourse and lead to Tongji Gate (the gate of the wall of Hankou Old Town), a Y-shaped road was formed, and this road structure was preserved in the construction of the Russian Concession ( Figure 12) (Zhu 2014). Panoffs' Mansion is exactly located at this Y-shaped intersection. The planar contour complies with the triangle plot which is not common in Chinese cities, while radial roads are frequently used in the urban planning in occidental cities, where there are a number of triangle and fanned blocks with acute angles. Occidental architects often treat buildings at acute angles as arcs or cut them, which was inherited in the design of Panoffs' Mansion.
The edges along the Dongting Street, Poyang Street, Lanling Road respectively are 101.7 m, 100.1 m, 43.7 m respectively. Due to the long street interface, the building is divided into two parts respectively called Larger Bagong and Smaller Bagong, each enclosing an inner courtyard. The northern part of Larger Bagong is connected to the southern part of Smaller Bagong, and the interface is perpendicular to Dongting Street, leaving a 2.5-meter-wide gap between the two apartments. This plane divides the triangular inner courtyard into two parts by an intermediate connection volume, and the space in the connection volume are used as service rooms.
The plane of Larger Bagong is an irregular quadrilateral, with a length of 36.5 m, 23.4 m and 43.3 m along the edge of Dongting Street, Poyang Street and Lanling Road respectively. The side adjacent to Smaller Bagong is 43.1 m in length; the junction is 12.6 m in length and 2.5 m in width. The plane of Smaller Bagong is a right triangle, with a length of 62.7 m and 70.2 m along the edge of Dongting Street and Poyang Street respectively, and 36.6 m of the side adjacent to Larger Bagong. The acute angle in the plane is cut into the facade facing the intersection and is used as one of the entrances of the apartment. The acute angle towards the intersection of Lihuangpi Road and Dongting Street is processed into an arc, with the top as a vault and the ground floor as the entrance (Figure 1).

Volume organization of the inner courtyard
The huge volume of is organized around the inner courtyard, which not only benefits ventilation and daylighting of the inside rooms of the apartment, but is also a transitional space for servants to enter the apartment. Different from the traditional Chinese residential courtyard as the core space of the residence and as the place to undertake production and accommodate the living activities of the residents, and from the ornamental features of the courtyards of the residence in European cities, the inner courtyard of Panoffs' Mansion, as a semiopen space connecting the street with the outer corridor, assumes a single function in daily life, mainly as the transitional and traffic space (Figure 13).
By the end of the 19th century, there were public houses for rent in Moscow, and even earlier, there were courtyards of multi-family dwellings with service facilities, for example, carriage sheds (Кулакова 2017). The line to home specifically designed for the host avoided the inner courtyard in Panoffs' Mansion. Therefore, it is likely to have the characteristics of the courtyards of public housing in Moscow at the time, assuming a similar logistical function. On account of openness of the inner courtyard, it lacks a sense of domain and privacy, which makes the estranged relationship among residents and their few daily activities. Compared with the courtyard of modern urban residence as the activity place of residents, the inner courtyard of Panoffs' Mansion is relatively passive, with weak function and few activities. But this method of volume organization of the building around the inner courtyard, and the boundary of the building is close to the boundary of the lot, make the building has a strong control over the block.

Differentiated spatial organization
By the end of the 19th century, a large number of multi-storey collective houses had appeared in European cities, and there were also multi-storey apartments for rent in Moscow, Russia (Кулакова 2017). The colonists brought the living mode of modern occidental cities to the original concession of Hankou.

Precisely positioned living mode
Panoffs' Mansion is not a common staff dormitory or apartment funded by foreign firms in the former concession of Hankou, but a commercial real estate funded by Panoff, which is the earliest practice of capital economy involved in terms of real estate of Hankou. After the completion, Crédit Foncier d'Extrême-Orient 15 was entrusted to rent the apartment to the foreign residents, without limitation of nationality or company affiliation. The ordinary employees of foreign banks and capitalists were both target tenants of Panoffs' Mansion. In order to meet the needs of different customers, the planes of units were diversified and more accurately positioned on the residents. The rudiment of modern unitary collective residence has been manifested in the organization of internal living space There are six self-contained sections in Panoffs' Mansion, among which 1 contains separate rooms along the outer corridor, and the other sections contain two units each storey. There are 27 units in total, 12 separate and 50 service rooms (excluding the additional storey). The units are mainly 2-bedroom or 3-bedroom, including living room, balcony, most equipped with separate toilets and kitchens. All the units have street-facing rooms with balconies outside the wall or interior balconies with arch column, with delightful daylighting and ventilation conditions, as well as views on the street. They are very close to the  layout of modern apartments, paying attention to the comfort of living. (Table 2).

1) Homogenization of the space inside Smaller Bagong
The area of single-unit of Smaller Bagong is generally between 160 ㎡~230 ㎡, each unit contains 3 ~ 4 bedrooms. The scale of each room is homogenous and the units lack core space, which type of unit organization occupies a mainstream position in the collective residence in the former concession of Hankou, for example, Jardine Apartment on Poyang Road on the northwest side of the Panoffs' Mansion (Figure 14). With a selfcontained section on the second floor of the southeast corner of Smaller Bagong as an example, there are two units on each floor, which have similar spatial layouts. Through the entrance door, one can enter the hallway which leads to the kitchen, bathroom and bedrooms. Because of smaller scale with 6-7 doors of the hallway, it is difficult to undertake functions other than indoor transportation, and the space is relatively negative. The kitchen and bathroom are close to the stairwell and open to the inner courtyard. The windows of the other rooms face the street if possible, the balconies are set up, reflecting the concern for living comfort. There are also individual rooms facing the inner courtyard or the interspace between Lager Bagong and Smaller Bagong, resulting in poor ventilation, daylighting and landscape views. The area of Unit A is about 160 ㎡ with 3 rooms   with an area of 26 to 27 ㎡. Among them, 2 rooms have a balcony facing the street, while the other room faces the interspace with a window (Figure 15).
The spatial organization of residence in the concession had a great influence on the modern residence in Hankou. The width of Jardine Apartment is only one room plus a corridor, which serves as the core of connecting rooms and vertical traffic. This type of terraced house is adopted by most of the Li-fen houses in Hankou. The floor plan of Continental Neighborhood, terraced houses with shops built in the 1930s, is very similar to that of Jardine Apartment (Figure 16). Golden Town Neighborhood, built at the same time, was the transformation from terraced housing to apartment, with the same spatial organization of one ladder to two units as Panoffs' Mansion. There was no vertical traffic inside units, and the differentiation of kitchen, bathroom, hall and bedroom was more obvious, which changed the previous life style of mixed functions ( Figure 17) (Chen 2017). This transformation had much to do with the "New Life Movement" promoted by the government at that time, why modern lifestyle in Europe was pursued by the urban middle class and became a symbol of social status. This lifestyle had already existed in Panoffs' Mansion, which was built in 1910.

2) Emphasis on indoor shared space and double entrances of Larger Bagong
The area of the units of Larger Bagong is larger than that of Smaller Bagong, but the number of rooms is smaller and the space scale is larger. The living hall is especially wide, focusing on indoor sharing life, with an area of 65 ~ 70 ㎡. The space is more ceremonial, with the windows open on both sides and two double doors facing the street and opening to the balcony. A living hall with an area of 68.6 ㎡, two rooms with an area of 32.9 square meters and 21.3 square meters, and two auxiliary rooms, are included in Unit E. The living hall is at the core of the unit and its space scale is much larger than other rooms. Each unit of Larger Bagong has double entrances: the resident entrance and the servant entrance. The residents enter the unit directly into the living hall, and the servants enter the unit through a transitional service room, which can be used as a preparation room or a kitchen. The two entrances are on either side of the unit, leading to different stairwells, one of which has a width of 1.8 m or 1.3 m for residents, while other has a width of only 0.9 m and is accessed from the inner courtyard for the servants. With the second floor of the selfcontained section on the east side of Larger Bagong as an example, the servant stairwell is shared; and Unit 5 shares the master stairwell with another unit on the southwest side, and Unit 6 possesses a resident stairwell separately ( Figure 18). Therefore, the designers attached importance to traffic line differentiation and privacy of the occupants.
As an investment-oriented real estate, compared with the staff apartments built by foreign firms, the target tenants of Panoffs' Mansion also included the upper-class residents who have higher requirements for living conditions. The apartment type of Big Bagong is aimed at this group of people. The indoor space organization is closer to the mansions and high-end residences in the concession area at that time. The residents are upper-class people with higher social status and more assets. The open living room meets their needs of social gathering. The Ivanoff's Residence, also located in the Russian Concession, was built in 1902 as the residence of another Russian tea merchant, Ivanoff. The residence is divided into three parts, left, middle and right. In each part, there is a room significantly larger than the others, and its function should be close to the living hall in the units of Larger Bagong, as a space for receive visitors, social or family public activities (Figure 19). But the hall in Ivanoff's Residence is not at the center of the unit like the hall in Panoffs' Mansion. In other Chinese mansions, whereas, the central position of the hall is prominent. The spatial organization of Tang Shengzhi Residence (1921) and Wu's Garden (1920s) centered on an open hall. This be probably because in the traditional Chinese residence, all the buildings and rooms are arranged around the courtyard. The residences of Chinese upper class in the concession were probably influenced by traditional houses (Figure 20,21). As a consequence, it is speculated that the spatial organization of units of Panoffs' Mansion may be affected by the core space of local traditional residence. The designer transformed the traditional courtyard core into the living hall core of modern unit, and made the indoor space more suitable for the lifestyle of the modern upper class.

Differentiated functional lines
The residential area and the service area are separated in Panoffs' Mansion. The flow lines of residents and servants are relatively independent, which reflects the protection of privacy of the residents.

1) Differentiation of residential and service areas
The units are mainly arranged towards Dongting Street and Lanling Road, and a few are arranged towards Poyang Road. The service rooms are mainly in the connection part between Larger Bagong and Smaller Bagong, with an area of 6.1 ~ 14.6 ㎡, whose windows are open to the corridor and a few to Poyang Road. There were no servants' rooms in the units, but the residents, who were mostly capitalists, aristocrats or senior intellectual, hired servants in Europe. The arrangement of the service rooms in the area with poor lighting and ventilation conditions means that the servants may be hired not by the residents personally, but by the apartment property management, in order to provide living services to the residents, which is similar to modern serviced apartments.

2) Differentiation of resident line and servant line
The lines of the service area and the residential area to units are independent of each other, connected through the outer corridors and the transition rooms. The residents enter the units through the vestibule and the stairwell, while the servants enter the service room through the inner courtyard, the outdoor stairs and corridor. In the design, the logistical flow is taken into account. There are a series of transitions in the sequence from the public street to the private units, so as to enhance privacy of the interior space ( Figure 22).
There are 9 entrances in Panoffs' Mansion. 6 of them at Dongting Street, Lanling Road and 2 street corners are entrances for the residents, leading to the stairwell through the vestibule, and then into the indoor space. The 2 arched doorways leading directly to the inner courtyard along Poyang Street are servants' entrances,      corridor is more open than the stairwell relatively. The outer corridor and the staircase leading to service rooms, are used by the servants, and are less private than the stairwell. In addition, the ground-floor entrance at the junction of Dongting Street, Poyang Street and Lihuangpi Road is the only one leading to the indoor space directly, which is usually used for commerce ( Figure 23).

Integrated architectural form of Chinese and European
The composition of the Panoffs' Mansion is classical, while the details are romantic.

Classical composition
The composition of the facade of Panoffs' Mansion draws heavily on the composition of Renaissance mansions, showing the classical style, while the colonial verandah is weak. On the facade, the windows on each floor correspond above and below, and the horizontal lines are used for distinguishing stores. There are eaves on the top to emphasize the horizontal order, but the windows are different in shape and size, with lintels in styles of mountain flower, arch and strip, so as to form a sense of orderly without being monotonous and serious. The design of the facade attempts to achieve a symmetrical composition, though the interior space is not completely  symmetrical ( Figure 24). With the facade along Dongting Street as an example, the balconies and windows on the facades of the two units of the self-contained section are symmetrical, and also the facades of the two adjacent self-contained sections of Smaller Bagong are characterized by symmetrical composition. In addition, the elements of arch have been applied frequently, such as the arched entrance on the ground floor, some of the arched   window and the interior balcony with arch on the columns on the second and third floors of Smaller Bagong (Figure 25, 26). Some of the overhanging balconies apply Doric Column, while the entrance porch applies Ionic Column. The combination of different columns enriches the form of the facade.
While the two square tent domes on Lanling Road had been demolished, the only remaining round one at the intersection on Lihuangpi Road is the most iconic design (Figure 27). The whole dome is white, shaped like a helmet, with a vertical point on the top, which becomes a unique urban landscape standing on the corner of the street. Standing at the intersection and looking at Panoffs' Mansion, the façade with curves, the dome on the top and the receding walls on both sides form a strong perspective, making the dome visually taller and strengthening the control of urban corner space, which is exactly the design technique that European architects are good at applying in terms of spatial perspective ( Figure 28).

Romantic details
The facade is mainly decorated by materials stone and black iron. Curved elements are applied to detailed decoration, which enriches the facade form of the building, neutralizes the solemn temperament of classicism, and makes the apartment more interesting for life. It can be seen that the solemn and dignified character of the building had been gradually weakened, while household atmosphere and improvement of living quality were taken more seriously. "The exterior wall is made of clay bricks, which are in the form of clear water joints, and part of walls such as window covers are the color of masonry" (Zhang 2016). The facade materials of the two apartments are not exactly the same: the ground floor Smaller Bagong is plastered with cement mortar outside the brick wall, and attached with decorative bricks with carved patterns. And the bottom is a stone foundation, showing a similar texture like the scabble 16 walls on the ground floor of Renaissance mansions. The plinth of Larger Bagong is protected by the cement mortar layer, and the walls above plinth are all clear-water brick walls.   Partial bricks are recessed, forming an appearance like big brick with several blocks combined, making the facade more rugged (Figure 29).
The facade along the street is not common, compared with those screen-style facades of Renaissance mansions, but balconies are set up as much as possible. Curved iron railings are applied to most of the overhanging balconies and all the interior balconies of Larger Bagong, and stone aquarium-shaped railings are applied to some balconies of Smaller Bagong (Figure 30). The facade along the street is enriched to enhance the building's openness to the street, and from the balcony the occupants can enjoy the street sight and human activities on the street. The lintel at the entrances of the apartment is engraved with curved patterns, and the top of the two entrances at the corner of Lanling Road is engraved with "1910" surrounded by oval patterns (Figures 31,32).

Regional components
Panoffs' Mansion applied some regional architectural components, the most representative of which is the shutter. Hankou belongs to the subtropical monsoon climate, where summer is hot and rainy. Louvers are widely used in local buildings for ventilation, sun shading and rain blocking. The shutters were fixed to the window frame to adjust the angle and thus the light. Louvres are used for the windows and balcony doors in Panoffs' Mansion, where a layer of wooden louvres is installed on the outside of the glass doors or windows, creating a structure of double window (Figure 33). The orientation of Panoffs' Mansion is mainly northeast, southeast and southwest, and the shutters can block the intense sunlight and keep ventilation in the hot summer.
In addition, there are some Chinese elements in the decoration of the building components. Part of the Dongting Street facade has a wing-shaped component on each side of the top of the column, next to the beam. This tiny component does not play the role of a structure, but is only as decorations, and its shape and carving pattern are very similar to the "Que-ti 17 " under the beam of traditional Chinese architecture (Figure 35,36). The pattern on the handrail of the public staircase in the mansion resembles the pattern "Hui" commonly seen in ancient Chinese art, which is named because it resembles the Chinese character "回" (Figure 37). This pattern originated in the pottery of the Neolithic Age, was commonly seen in the bronze wares of the Shang and Zhou Dynasties (17th century BC to 256 BC), and was revived in the Song, Ming and Qing Dynasties (10th century to the early 20th century), when it was widely used in various daily necessities. The iron balustrade on the facade along Poyang Street resembles ancient Chinese circular coins with square holes 18 (Figure 34).

Conclusion
The modern collective residence in Hankou Concession was born at the end of the feudal period in China, originally to meet the housing needs of colonists. From the perspective of urban planning, the grid planning of the concession forms a contrasting urban texture with Hankou Old Town. This grid road network reappeared in the then undeveloped area to the north of Hankou Old City, which is also commonly seen in modern urban planning. From the perspective of residential mode, the western spatial organization and residential mode had a profound impact on the development of residential architecture in Hankou. The most distinctive residential "Li-fen" residence in modern Hankow is a new residential form that integrates concession residence and traditional residence. In terms of architectural style, influenced by the trend of classical revival in Europe and colonial style in Southeast Asia, the collective residences in the concession are dominated by classical and colonial styles, combining the characteristics of house of various countries and adopting some regional elements.
Based on a series of field investigation and historical data of surveying and mapping, the plane of Panoffs' Mansion is recovered. The triangular block at which Panoffs' Mansion is located was the result of the Y-shaped intersection from the British Concession to the French Concession, as the result of devastating volume of Panoffs' Mansion, which occupies the whole block. By analyzing the restored building plane and comparing the differences in the spatial organization of Larger Bagong and Smaller Bagong, the differences of residents and living modes were deduced. Functional differentiation of the unit makes it more to adapt to the modern lifestyle. The typical classical style is presented on the facade, while the details are a blend of romantic, Russian national styles and regional elements. In fact, the architectural style of the mansion is not unique among the modern buildings in Hankou concession, but its building volume and the spatial organization of units in collective residence are quite distinctive. The unit type of collective residence was gradually rising in 1930s in Hankou. Therefore, it can be inferred that Panoffs' Mansion is the forerunner of modern unit housing in Hankou, and has a profound influence on the spatial pattern of residential buildings in Hankou.
Panoffs' Mansion is particular in the Hankou modern collective houses. However, it is difficult to extend its living mode to other collective houses in the former concession because of its unique feature of commercial real estate. More cases need to be surveyed and reconstructed, in order to explore the modern collective houses in Hankou systematically, which calls for further research.

Disclosure statement
No potential conflict of interest was reported by the author(s).