Ferrara

The Este dukes ruled Ferrara for three centuries and in 1492 commissioned the Addizione Erculea, a planned expansion that doubled the city on a grid with straight streets and a diamond-faceted palace — often called the first piece of modern town planning in Europe. The court kept Ariosto, Tasso and, briefly, Copernicus, and the castle has a moat still full of water in the middle of town.