The Proportions of the Addizione Erculea

Abstract

The Addizione Erculea, Duke Ercole I’s expansion of Ferrara, has been the subject of numerous studies from historical, artistic, and geometrical-compositional standpoints. The reasoning underlying its design has been researched by examining both modern and historic plans and maps and comparing them against the knowledge of the period. Rossetti’s great work of urban design can easily be studied based on the geometry of the axes, the layout of the city walls, and the points they connect. Nonetheless, the grandeur of the work implies an equally impressive capacity to govern the territory through the use of topographical (land surveying) and cadastral (land registry) tools: the geometry of lengths and angles, on the one hand, and the geometry of surface areas, on the other. While the logic behind the linear geometries has been linked in previous studies to cultural paradigms (such as astrological alignments and symbolic references), the geometries of the surface areas were more closely driven by the forces of the administration of justice, the economy, and politics. In light of this model, references to Pellegrino Prisciani’s Proportionabilis et commensurata designatio urbis and comparative studies between his rendering and the present layout of the historic center of Ferrara begin to take on new meanings. The aim of this study is to provide a new key to interpret the work of Biagio Rossetti and Pellegrino Prisciani, highlighting the geometrical and topographical expertise of these intellectual figures to whom Ercole I d’Este, the Duke of Ferrara, entrusted the expansion of the city. Together they succeeded in giving concrete form to their urban design in a way that maintained symbolic and cultural values while at the same time satisfying demands of an economic and political nature.

From a survey of the surface areas, a new contribution to the research on Biagio Rossetti’s urban planning project.