The Rocca Brancaleone was erected by the Venetians in 1457, was part of the city walls and was built in two parts, the Rocca and the Citadel. Joined by the curtain walls the Rocca is a wide quadrilateral of 2180 square metres with impressive circular towers at each corner. Surrounded by walls with a fortified door the Citadel covers an area if 14,000 square metres, with two round towers at two corners and two semi-circular ones along the wall curtains.