Abstract
Like many cities founded by the Romans, Florence, the Roman Florentia, was oriented to the cardinal points. The major streets, a north-south cardo and east-west decumanus, met in the center of the rectangular walled town. A gate was located at each of the four intersections of major street and city wall. A grid of secondary streets divided the city into blocks. The steps traced in this paper indicate a logical way in which the colony of Florence could have been laid out, consistent with what is known of Roman practices and with the observable traces of the Roman settlement. Relatively simple geometrical operations integrate the city with its landscape, which is linked with the cosmos through the path of the sun, providing the initial positioning of the city. What at first glance may seem to be a pragmatic adaptation to the site conditions is shown to be a rigorous geometric relationship, predicated on using a meaningful set of whole numbers, in an affirmation of the genius loci of Florentia.
First published as: Carol Martin Watts , “The Geometry of the Master Plan of Roman Florence and its Surroundings”, pp. 169–181 in Nexus III: Architecture and Mathematics, ed. Kim Williams, Ospedaletto (Pisa): Pacini Editore, 2000.
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- 1.
This chapter is the outgrowth of joint research with Donald J. Watts on the Roman layers under the Duomo of Florence . We presented this ongoing work at the Nexus’98 conference in Mantua, Italy, “Roman Code”, and the 1998 Bridges Conference, Winfield, Kansas, “Traces of the Geometrical Ordering of Roman Florence”. I wish to acknowledge the important contributions of Donald J. Watts to the hypothesis presented in this chapter, as well as his work on the illustrations. What follows is based on maps at 1:5,000 and 1:25,000 published in 1996 by the Istituto Geografico Militare, Florence, based on satellite imagery. Given the scale involved, it was impossible to personally take measurements.
- 2.
Little remains of Roman Florence, but recently there has been a revived interest in understanding the city’s origins. A good recent source is Alle Origini di Firenze, dalla Preistoria alla Citta Romana (Capecchi 1996), the catalogue for an exhibition at the Museo Firenze Come’era. Although the two main streets and the location of city gates followed typical Roman typology, the city wall of Florentia appears to have deviated from the ideal rectangle in the southeast corner, to respond to topography of the site near the river, as revealed by excavations below the Piazza della Signoria . In the late nineteenth century the urban renewal of a large area around the present Piazza della Repubblica brought to light many Roman remains, but did not allow time for systematic excavation. They were recorded by the architect Corinto Corinti , whose drawings and notebooks are catalogued in (Orefice 1986). Today one can visit the south gate of the Roman city, see the outline of the city wall on the east marked in the street at one point, and visit the crypt of Santa Reparata below the Duomo, where a sequence of churches were built over Roman housing. A Roman house excavated in the late 19th century can also be glimpsed below the Baptistery of San Giovanni .
- 3.
Dilke (1971) is a comprehensive work on what is known of Roman surveying techniques and practices.
- 4.
The Roman foot (as used in Florence) was 0.295 m = 1 Roman foot.
- 5.
For the centuriation around Florence see Instituto Geografico Militare (2003, PL 27–28).
- 6.
The usual explanation for the differing orientations has been that the centuriation, for pragmatic reasons, parallels the long, narrow valley and is thus a result of topography, while the city follows established preferences to orient to the cardinal points, for cosmological reasons.
- 7.
According to Dilke (1971: 89), the east–west decumanus maximus was typically the first line established in the Roman surveying process. The augur typically faced east.
- 8.
This road may have crossed the river near the site of the city. One theory for the location of Florence at this point has been that the Arno was navigable up to this point, or that it was a natural crossing point for the pre-existing road system, at or near the site of the present-day Ponte Vecchio.
- 9.
The angle is described as 30° 58′ or about 31° by Hardie (1965: 132). The fact that this is an angle based on a 3:5 triangle was pointed out by John Peterson, in personal correspondence instigated after viewing his Internet site. In an unpublished paper presented at the Theoretical Roman Archaeology conference in 1998 he discussed meaning in the geometry of Roman planned landscapes, including Florence. Peterson identifies a number of whole number ratios which can be expressed as triangles which he finds used in Roman surveying.
- 10.
Continuing the Sacred Cut arcs creates a lozenge or petal-like form, and the complete Sacred Cut operation would create four such petals, perhaps giving rise to the name for the city, Florentia. Such a flower-like form was also common in Roman mosaic patterns.
- 11.
A similar accommodation occurs between dimensions commonly used for Roman house regulating dimensions and block sizes. Another parallel is with pavement patterns, where a border zone mediates different dimensions and accommodates irregularities between the outer wall of a room and its mosaic pattern.
- 12.
Archaeological evidence of the western gate has not been located.
References
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———. 1992. The Role of Monuments in the Geometrical Ordering of the Roman Master Plan of Gerasa. Journal of the Society of Architectural Historians. 51(3): 306–314.
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Watts, C.M. (2015). The Geometry of the Master Plan of Roman Florence and Its Surroundings. In: Williams, K., Ostwald, M. (eds) Architecture and Mathematics from Antiquity to the Future. Birkhäuser, Cham. https://doi.org/10.1007/978-3-319-00137-1_12
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