The current square is the result of heavy restoration carried out at the end of the 800s by the architect Giuseppe Partini, that altered its general image, building on and adding new structures, in the neo-gothic style of the time.
At the back of the square, essentially extracted from the garden of the adjacent Palazzo Spannocchi, the ninth century façade (by Partini) of the Salimberi Fortress stands out. It is one of the most imposing, complex and strengthened fortresses of medieval Siena, and the home of the great Salimbeni family until they were hunted from Siena and their possessions confiscated (in 1419).