The main historic buildings of the town are located in this large rectangular square. The cathedral, Duomo di San Martino, has a white marble façade, in the centre of which is a huge rose window surmounted by the coats of arms of the Medici and the Papacy. The square is also home to the Palazzo Moroni, the church of Sant'Agostino, the 14C Palazzo Pretorio, the clock tower (1560) and the remains of the Rocchetta Arighina, also known as the Porta Pisa.