A city is a process that is expressed in its becoming dynamic over the centuries. The plan of a city requires interpreters and transcribers, who can at any moment betray the original conception, diminish its tension, hinder its development. It could be said that an urban planner needs, among many other qualities, a good dose of luck, as his inspiration must be understood, shared and concretized by posterity for several generations. But luck depends above all on the strength of the initial artistic intention: on the resistance that the plan opposes, due to its intrinsic coherence, to those who want to undermine it and, at the same time, on its degree of receptivity to the building contributions that integrate it over time. Ferrara is, in this sense, unique. Biagio Rossetti’s plan shaped its face and structure for centuries. *
Bruno Zevi, Saper vedere la Città.
Ferrara is conceived by the mind of a man capable of a perfect balance between the tendency to abstract rationalism and banal empiricism. While rejecting the theories of Filarete, celebrated by the culture of the period and very popular with the lords, and organically resolving the union of the old city with the new, Rossetti infuses a deep classical spirit into his work. The Albertian flavor of the mixture of knowledge of the medieval tradition and the ancient way of working permeates the project of the Herculean Addition. In particular, the urban design clearly expresses the attention to the tradition of classical Romanism.
The reference to the castramentationem is evident from the cardus and decumanus setting. It is no coincidence that the city hinge, moving away from the canonical orthogonality, identifies the same direction as that of the Roman castro in the ancient core. A clear homage to the Chthonian gods.
The eidogenesis of the castro is strongly linked to measurement, rational control, the possibility of orienting oneself with confidence in a world almost devoid of vision from above.
From the crossroads of the Palazzo dei Diamanti, the new geometric city center, the main axes branch off and find a solution of continuity in the doors near the walls: equidistant from the origin. The exact half of this distance accurately identifies Rossetti’s architectures; to the north-east, along an imaginary line that connects the Punta della Montagnola, the church of San Cristoforo alla Certosa, to the east that of San Benedetto while, to the south, the Este castle contends the polarity of the Palazzo dei Diamanti. From this, in the middle of the radius that inscribes the city, Porta Paola and the church of San Francesco meet.
It is also possible to identify the construction of an “astrological square”, a birth chart by Pellegrino Prisciani (councilor at the court of Ercole I d’Este), to draw the course of the walls to the north. This configuration would see the center of the new city as the acme of the astrological theme.
Exact measurements dimension the urban plan and organize the space making it on a human scale.
The center, the intersection of the two main axes, is the origin of a precise ordering theory of the world; theory dear to classical Roman times, accustomed to taking possession of the territory through a system of centuriation; cataloging of agricultural land that has as its reference cardo and decumanus citizens. The square becomes an expression of the earthly dimension, of the spatial three-dimensionality, as opposed to the “nunc fluens” of the celestial vault. Square shape, symbolic, which originates from work and from the dimension of human and animal fatigue: the juger indicates the arable area by two oxen “yoked” in a day.
Rossetti, having to make his plan commensurable and easy to the habitual spatial experiences of the people of Ferrara, chooses Biolca as the fundamental unit of measurement.
This ancient Ferrara unit of measurement, parallel to the Roman one, expresses the area of land that can be worked by a farmer (bifolco, bifolca, biolca). The medieval tradition, not unrelated to modular dimensional relationships, thus provides the matrix for measuring the entire plan of the Addition. The fundamental unit and all the related submodules can be found in the development of the city up to the present day. The same Palazzo dei Diamanti occupies an area equal to one module. Seven modules identify exactly the monuments mentioned above, while the doubling inscribes the entire city. Counting ten units, on the maximum cardo, we meet the Door of the Angels.
This dense conceptual texture structures the strength of Rossett’s project and constitutes its geometric backbone that hosts infinite conceptual refinements and masterful architectural solutions.
Any architectural project can only observe and be inspired by this clarity, drawing lifeblood from the peculiarities of this urban form, unique in the panorama of European cities.
Dimensional relationship between the modules
