Rocca Brancaleone was built by the Venetians in 1457 with the purpose of reinforcing the defensive structures of the city. It stood in an uninhabited area to the north-east of the city walls, close to the road that led to Venice. The main construction of the fortress was the Rocca itself, a wide quadrilateral surface measuring 2180 square metres with four impressing circular towers at the corners, joined by walls. To the south rises the socalled Cittadella, a 14.000 square-meter area once used for the accommodation of the garrisons, for the storage of foodstuffs and arms, for the stalls and for other purposes.