For the critical historical picture I made use of the numerous extant works, foremost among which was Zevi's monograph on Rossetti. To render visually the urban structure of the city I used graphics and animated drawings by Professor Milani. But it was precisely in defining that structure that I encountered most difficulty. The town planning and topographical data were taken from plans from before 1492, when work on the extensions began. Chronicles and other documents relating to the city helped me deduce other information while I was also able to access the Pasi archives, which contain a collection of notarized deeds of sale.
Through the examination of these data and the continuous comparison between these and other data deduced from the various plans extant in the municipal library, we managed to define a precise and detailed map of the city as it was in 1482. The result was completely original.
In developing his plan, Biagio Rossetti followed the ideas and requirements of Duke Ercole I as well as the new principles of the Renaissance. The duke's immediate purpose was the defence of the city and of his own properties in the zone to the north, more exposed to the incursions of the Venetian Republic, but the expansion of the city was also an affirmation of power with regard to the other Italian cities.
Rossetti devised his plan according to this brief. He included the cultivated zone and the pleasaunces of Barchetto and Belfiore in the Addizione but left out the large and populous settlement known as La Pioppa, east of the medieval city. He also took account of the suburbs and managed to blend the Renaissance and Medieval concepts into a single reality suggesting an unforced historical and cultural continuity.
In particular he conceived a Renaissance-type street plan that linked up the two ducal pleasaunces by intersecting with another road that connected the two main exits, the Porta a Po and the Porta a Mare. At the crossroads he put the buildings of the First Quadrivium, outstanding among which is the Palazzo dei Diamanti, the ideal centre of the Addizione.
He also designed the urban elements (piazza Nuova, today Piazza Ariostea; three churches: San Benedetto, San Giovanni Battista, and Santa Maria della Consolazione) that served as a counterbalance to those of the old city (the cathedral with the square and the old centre) and in designing the streets he put into practice the criterion of the green space (parks and gardens) as architectonic elements of the town plan.
His genius lay above all in the balance with which he produced his town plan, the first one to be designed according to the tenets of the Renaissance, bequeathing us a living, organic city rather than an ideal layout.
Opting for a blend of ancient and modern, Rossetti constructed key buildings that block off the perspective of one street, but open it up for another. His basic road layout left room for the insertion of smaller buildings alongside the noble palazzi and, above all, thanks to these stylistic characteristics Rossi defied his successors to ignore the appeal of his buildings, his streets, and his green spaces, thus transforming Ferrara into an admirable example of harmonious town planning that has retained its character over the centuries, resisting even the worst assaults of modern speculative building.