Piazza Maggiore is the main square of Bologna, measuring 115 meters in length and 60 meters in width, and is surrounded by the most important buildings of the medieval city. The oldest is the Palazzo del Podestà, which closes off the square to the north; it dates back to 1200 and is surmounted by the Torre dell'Arengo, which by ringing its bell summoned the people. Palazzo Re Enzo was soon added to this, under which the cross vault of a pedestrian crossroads opens.