lE CorBuSIEr: urBan VISIonS THrouGH THrESHolDS

. In Le Corbusier’s work the threshold is represented like a revealing and enigmatic space that define the relations of the limit or boundary, the separation and the union between the buildings and the urban spaces, and the space that defines, qualifies and characterises the minimum condition of urbanity of any work of architecture, irrespective of its use or scale. Through an analysis of the draws based on the study of the six notebooks of The Voyage d’Orient (1911), and of the study of the urban settings visited, we verified that the threshold is, for Le Corbusier, a space or sequence of spaces organised under the idea of “plan” of variable thickness or extension, that includes both criteria and guidelines of order as well as solutions for managing the limits or boundaries in architecture, as well as its relation with space and the involvement with its surroundings, that is to say, we have also focused on highlighting how the architecture in itself, attends to an order that as well as being articulated and unitary, is extended by means of doors, frames, courtyards, terraces, sheds and exterior spaces, that incorporate both the nearby urban landscape as well as the distant cityscape.


Le Corbusier. Vers une architecture
The urban vision in history: [1907][1908][1909][1910][1911][1912][1913][1914][1915][1916][1917][1918][1919][1920][1921][1922][1923][1924][1925] The interest of Le Corbusier in urban themes began very early on. The preparation for the book "Les construction des villes", from 1910, at the age of 22, until 1915, was his first opportunity to make a reflection about the city and the urban space. The pretext for that Le Corbusier worked on the elaboration of "Les construction des villes", in two main stages: the first from the summer until the autumn of 1910; the second, after almost five years, from June until September 1915. Afterwards, between 1922and 1925 he would return to the project, writing the text once again, although he conserved the general structure of the version of 1910 for the book that would be published under the name of "Urban planning" (Allen Brooks 1997).
The first stage coincided with his first trip to Germany and which was carried out between March 1910 and May 1911, while, during the second stage, in 1915, he would resume his studies about the city but this time in the Bibliothèque Nationale de Paris. This was until the summer when he would return to Chaux de Fonds, his hometown. From his trip to Tuscany until his journey to the East, including his fundamental trip to Germany, Jeanneret shifts the focus of his interest towards urban themes as shown by his sketches, drawings, photographs and notes, interest that will be reflected during all of his life (Fig. 1). From 1907From until 1915, by means of the study of the urban spaces of the historical city, he learnt some of the basic skills which would serve him, so as to subsequently formulate criteria of order and architectural solutions for the configuration of the modern urban space (Sequeira 2009).
The relation between the urban space and history in Le Corbusier is as obvious as it is complex, and it is as evident as it is difficult to synthesise. Much has been written about this topic, a recent example of this being the book L'Italia di Le Corbusier from 2012 (Talamona 2012), a catalogue of the homonymous exhibition, which emphasises the fundamental role of the historical Italian urban spaces in the consolidation of his vision as draughtsman, photographer, theoretical architect and designer of projects. The theme is so wide that we could get lost among the large amount of information available about the Swiss maestro and in which he himself elaborated and ordered. For this reason we will focus our analysis on the relation between the master and the history so as to understand his vision of the urban space in a theme and field of specific study: The reflection about the notion of the threshold as a defining element and/or space of the limit between the inside and the outside, taking as general references the series of notes, sketches and drawings from the journeys carried out in 1907, 1910 and 1911 and the reflections belonging to the book "Les construction des villes" and "Vers une architecture" and as a specific reference to the field of study is restricted and narrowed to the contents of the six notebooks of the Journey to the East.
The idea is for us to get close to how the threshold is understood and represented, the revealing and enigmatic space that define the relations of the limit or boundary, the separation and the union between the buildings and the urban spaces, and the space that defines, qualifies and characterises the minimum condition of urbanity of any work of architecture, irrespective of its use or scale. It is Le Corbusier himself who suggests a point of view for starting to get a glimpse of his positions regarding the theme. A careful review, again and again, of the pages of the notebooks of the Journey to the East, produced between the 23rd May and the 1st December 1911, and which notable authors 1 have considered to be the pillars of their learning, have led us to define our approach. Many of the drawings in the notebooks show the recurrent vision of an observer, the young Jeanneret, who very often contemplates the outside from an interior space, and that in turn this exterior leads to, and is in dialogue with another, exterior further away. The drawings show us different types of urban spaces, entrances, hallways, courtyards, squares and gardens through a conscious look, and in a reiterated and repeated way, highlights the presence of walls with openings, doors and spaces, which together make up a varied repertoire of "thresholds" of the buildings and places visited.
The vision of Le Corbusier is so mature that it raises the suspicion that the journey was more a way of checking and verifying his ideas and his previous studies, than a totally new discovery: in fact these reiterative approaches towards recurrent themes are the proof of the early urban vocation of his own projects, leaving us with a lesson that still today allows us to understand that the exterior and interior spaces make up a unity, and that the historic buildings and urban spaces that he visited during his journey continue to be an inexhaustible source of learning, learning that he himself would represent again and again in many of his subsequent projects.

The threshold between the inside and the outside
The threshold is one of the crucial themes of architecture that refers to the limit or boundary, and to its multiple possibilities in the configuration of the spaces. In the case that we are dealing with, we are interested in approaching the understanding of the limit, extending it to the idea of threshold, that is to say, to the possibilities of spatial configuration and its variable thickness (from the verticality of the wall and the door, and the horizontality of the landing and steps, until the extended spatial relations between the inside and outside of the buildings) introducing the notion of urban minimum (Sichenze 1995), a quality that makes a building relate to, and be inserted in, the place by means of architectural solutions of relation between inside and outside which Le Corbusier knew how to recognise, exemplify and reflect in his notes and drawings from the Journey to the East in 1911. In the writings of Le Corbusier there doesn't appear a clear and definitive definition of what we consider to be "threshold", although the term appears used a few times 2 , but what we can recognise in the writings, and above all in the drawings, is that there are more than enough explanations and demonstrations of what he defines as a key relation for architecture: "L'extérieur est le resultant d'un intérieur" and "Le dehors est toujours un dedans" (Le Corbusier 1924).
In terms of the distinct definitions of threshold, various meanings have been found that vary according to each language. Initially we can consider that the word for threshold in Spanish "umbral" 3 , comes from "lumbral", that has its root in the Latin term limināris, and which in turn is derived from limen, -ĭnis "umbral", the inflection of lumen "lumbre", which represents the doorsill or lower part of the entrance door of a house; in English this part could either be 'doorsill' or 'threshold' 4 which is equivalent to the constructive piece that serves for the transition between the interior flooring and the exterior paving, while 'doorway' represents an opening of the building, a space in front of the door which is for entering and/or leaving, and also the upper part of the door and that has the function of lintel. From all of this we can deduce that the threshold is the part you step on and/or cross over to enter or leave a building.
Furthermore, there exists a familiarity in the terms used of the equivalent form in Italian, German and French. Sòglia 5 , schwelle 6 and seuil 7 , all come from the Latin solea, from solum, (base), that despite the fact that they do not suggest to us a reference to a constructive element that you step on when you enter, they do contribute other architectural elements and spaces that by analogy not only refer us to the verticality and flatness of the door, but also to a horizontality and three-dimensional aspect. In this way, we can therefore refer to other boundary elements such as the banister and railings, but also large delimited spaces which are covered and extended, thus highlighting the relation that exists between the terms umbra (shade), which approach us to the meaning of umbráculo or shaded structure, as a device with which you provide shade for a place. In general, reference is made to elements and spaces that you have to cross over so as to enter or perceive the passing from one place or setting to another. Doors and windows, perforations such as frames; or landings, stairways and floors as extensions; extended covered spaces as prolongations or connections, are all together architectural solutions that exercise as a mediation between the building and its parts and the surroundings.
In our interest of approaching the conception of the urban space through the thresholds depicted in the vision of Le Corbusier, we have selected and extrapolated in the 6 notebooks of his Journey to the East, all the drawings (48 double pages) that depict different types of spaces of transition related to the urban spaces and we have put together a series and/or sequences of drawings that reveal multiple nuances in the particular configuration of a threshold, or sequence of thresholds; the doors and their thicknesses, the extended stairs, the passages and corridors, the exterior and interior extension of the "interiorised exteriors". 5 Italiano: soglia. s. f. [lat. sŏlea «pianta del piede; suola», con svolgimento semantico prob. influenzato dal germ. swalja (cfr. ted. Schwelle) «soglia»]. a. Lastra di pietra, striscia di cemento o, più raramente, di legno che unisce al livello del pavimento gli stipiti di una porta o di altri vani d'ingresso. b. fig. Inizio, principio (cfr. l'uso analogo di limitare1). c. Nel linguaggio dell'edilizia (per analogia con quella del vano della porta), la copertura, generalmente di pietra, del parapetto della finestra, comunem. chiamata davanzale; quando il parapetto è molto largo, o si vuole coprire lo spazio delimitato dagli sguinci e dal parapetto, si dispone dietro la soglia, in prosecuzione di essa o un poco più bassa, la controsoglia, lastra piana di pietra o, più spesso, di legno (Treccani 2013 In a second group made up of two images, the two doors can be found in very different urban conditions, one in the Villa Adriana, the other in the city of Fiesole. However Le Corbusier's attention is caught by the presence of some trees that enhance and give monumentality to the entrance, and which he draws, above all in the second case, with great force and expressiveness.
Finally, in this last group, he describes the different types of openings and the effects of the shade and the depth that can be produced in the interior, and on the façade of the monastery and on the side wall of the Villa Adriana.  On various occasions, Le Corbusier depicts the entrance door, highlighting by means of the drawing, and sometimes with his own comments, specific characteristics such as the decorative elements, the moldings or textures, and constantly noting down the main measurements and showing the thickness and the depth more than the plan. We can see how this view is reflected in a series of drawings.
In a first group of images he draws various entrance doors from the streets and in each one of them he catches the interest by highlighting at the The extended staircases The staircases, like the doors, are minimum spaces of urbanity in all the buildings. Le Corbusier portrays two types of staircases that fulfil the function of mediation with the urban space: those that define a connection and access to an exterior space, like those of Bursa and of Tivoli, and that are perceived as extended plans related to the landscape. And the other group of staircases that fulfil the function of allowing access to a building. In this case, he points out that the staircase is perceived as an annexed volume or body that prolongs and extends the building towards the exterior urban space.

Passages and corridors
The three spaces depicted are vaulted interior routes, leading from an interior to an exterior space. The condition of the threshold is defined by means of an elongated space, dynamic with a beginning and an end well established, and moreover with a change of level in both of them. The note of Le Corbusier that accompanies this drawing is a very precise description of the spatial richness that a threshold can manage to produce in a building and its relation with the outside: "It is masterful. I am drawing this from the threshold of the cella. The altar of the Forum is in the best place and just beyond the colonnade, making up a great scene. Then you can see the plinths in the background; and then the ones on the right. The tiled vestibule is joined to the Forum. To the right is a triumphal arch, very close by. It is necessary that there is just a shaft of morning sun. This blackens everything; but the paving remains white. Further beyond, the large concentration of the glaucous, or light green, of the mountains. The measurements are the cause of this beauty." (Notebook 4, page 102). To draw the temple of Jupiter, he "will have to dodge the altar that is right on the axis of the temple. Once you have climbed the steps, from its pronaos, outlines a new view of the Forum. A panorama in which imaginatively reinstates nonexistent pronaos colonnade." (Daza 2008).

The exterior prolongation of the interior
It is worth pointing out here the fact that in this case he uses the word seuil (threshold), to define his location inside the temple, but even more important is the fact that with his drawing he reconstructs the colonnade so as to transmit, in a more precise way, the spatial feeling of an observer who, from an interior space, observes a profound scene made up of a spatial sequence that begins in the cella and finishes in the mountains. The point of view chosen by Le Corbusier reaffirms this view that aims to portray in a recurrent way the relations between the inside and the outside extended as a prolongation towards the urban space and the landscape. This theme is also recurring in other drawings where he once again depicts a threshold through a colonnade, such as in Athens or in the Villa Adriana, or through a frame composed of a horizontal line of the ground and the vertical lines of the side walls once again in the Villa Adriana, as well as through another type of framing defined by an arch which produces a spatial effect similar to a door facing outwards as in Pompeii, in Villa Adriana and in the Baths of Caracalla.
Finally in his characterisation of the different types of thresholds, those which show a relation between various exterior spaces take on particular importance, as is the case of the Charterhouse of Ema, where the exterior gallery relates with an exterior defined courtyard located at a lower level, or in the Villa Adriana or the Villa d'Este, where different spaces connect between each other in a spatial sequence which expands the depth of the gardens and courtyards.  11. relation between the different exterior spaces observed from an interior space 11a,11b. Drawings of the view that there is from the passage towards the vegetable garden and towards the outside, beyond the limits of the Charterhouse of the Valley of Ema (notebook 6, pages 11, 13) / 11c. Drawing of Cortile of the library of Villa adriana; a merging between the plan and the section of the courtyard so as to highlight its depression related to its perimeter corridors lined with mosaics (notebook 5, page 40, 41) / 11d. Drawing of the ground floor and elevation of the Villa d'Este on his second visit, which fully reflects the transition that occurs between the two spaces. This is a proportional relationship between a rectangular space (the fountain of the owl) and a square space (the fountain of the emperor). The elevation includes the staggered transition of these spaces; in the background you can see part of the Villa and the triumphal arch of the Grotta di Diana (notebook 5, page 92, 93)

The interiorised exterior
The theme chosen by Le Corbusier in this series of drawings fixes the attention on the perception of the exterior spaces as if they were interior, recognising their character as defined spaces also when there is a relation with the landscape. The observer is sometimes inside and at other times outside the place represented, and the condition of the threshold remains associated with a spatial sequence where different characteristics are depicted of the urban spaces through enclosures and doors. It is also interesting to remember in Istanbul, Rome or Pompeii, Jeanneret has pursued transit and variations that have the openings as input light and directed towards objects of sacred origin (exiguum foramen). However, here in the auction of Canopus, it was found with a particular form of overhead lighting (Daza 2015).
In this sequence of the Villa Adriana, the view is focused from the outside towards the space of the exedra, where the condition of threshold leads to an interior space. Le Corbusier draws a sequence which always gets closer to the interior space through a door and finally emphasises the relation with the outside through an opening in the roof.
In this second sequence a complementary vision is reproduced of the previous one. In the exterior spaces in the Roman Forum and the Baths of Caracalla, Le Corbusier carries out his drawings based on a point of view in which the elements of the urban space clearly make the limits, an urban scenography that isn't closed, but frames another open space. He reconstructs a threshold space that serves, at the same time, to delimit, or define, an access, to open and finally to frame the background of a space further away.
The condition of the enclosure in the urban space very much caught the eye of Le Corbusier. In the drawings of the Villa d'Este, of the villa Adriana or the Square of Campidoglio, the common characteristics are highlighted with unidentified spaces such as the courtyard of a house or a balcony in a garden, in which the framing of the drawing and the point of view chosen depict courtyards, gardens and squares, emphasising their condition of being defined spaces which can be accessed by means of a highly defined door or entrance. In this series of drawings, however, the condition of the enclosure of the exterior spaces is perceived to be much bigger and extended, and the characteristics of the border that make up the access thresholds are much more permeable and lead to another sequence of urban spaces framed in the landscape. word seuil (threshold) on very few occasions, however there exists a constant reference to the relation between interior and exterior which is precisely the function exercised by the threshold in the spatial configuration of the act of entering, leaving or delimiting. All the drawings that we have selected show thresholds in different forms, categories and hierarchies, and the spaces represented, be they doors, stairs or transitions (passageways, exteriors as an extension from the interior, interiorised exteriors) fulfil an urban function of dignifying the entrance to the distinct spaces, or relating an inside with an outside, or configuring an exterior with a broader exterior. In 1924, in 2 nd edition of Vers une architecture, illustrated basically with drawings and photographs of the Journey to the East, the comparison of three drawings from the notebooks of the journey of 1911, two of the Villa Adriana and one of the Forum of Pompeii, he highlights the reflection about a key concept for the Swiss master in the interior-exterior relation: the idea of plan.  (Le Corbusier 1924: 149).
For Le Corbusier "a plan comes from the inside out and the outside is also an inside". In this book Le Corbusier uses the term "le plan" on various occasions. In chapter II Trois rappels a messieurs les architectes, III Le Plan (Three warnings to the gentlemen architects in the section III called "The Plan"), and later on in the chapter V Architecture II L'illusion des Plans ("Architecture" in the section II "The illusion of the plans"). The term apparently being the same -in French, is used in two different meanings according to its context. On the one hand, it is used to define the idea of order and of determination "of everything" abstract and also formal, that configures the system of relations that provide unity to the architecture. A law of order which is planned and developed spatially in extension and height, and one that is finally perceivable by man: Le plan est le générateur ("the plan is the generator"). And on the other hand, it is also used to emphasise the relation between the inside and the outside in architecture, "plan" -as "plano" translated in the Spanish version of the book, that focuses on showing how the materialisation of the constructive and spatial procedures, that is to say the "architecture", establishes an effective relation towards its setting based on its architectural elements. The two complementary meanings, refer us to the threshold as a space or sequence of spaces organised under the idea of "plan" of variable thickness or extension, that includes both criteria and guidelines of order as well as solutions for managing the limits or boundaries in architecture, as well as its relation with space and the involvement with its surroundings, that is to say, we have also focused on highlighting how the architecture in itself, attends to an order that as well as being articulated and unitary, is extended by means of doors, frames, courtyards, terraces, sheds and exterior spaces, that incorporate both the nearby urban landscape as well as the distant cityscape. This is the same viewpoint through which Le Corbusier depicted in his subsequent urban projects, notable spaces of relation: the drawings of the ground floors of projects such as the Palace of the Nations, in Geneva, of 1927Geneva, of -1928, the Palace of Centrosoyus in Moscow, of 1929-1930, the Swiss Pavilion in Paris, of 1930-1932, the Sanatorium Project in zurich, of 1934, or the Ministry of Education and Health in Rio de Janeiro, of 1936-1945, among many others, which all emphasise this "wide and extensive" look which accompanies him so recurrently on his trips and would continue accompanying him throughout his life. One of the so many lessons of history… reference list