The tower of St. Pancrazio, designed by the architect Giovanni Capula in 1305, was part of the Pisan fortress to defend the northern entrance of the Castello district of Cagliari. Built on the highest point of the hill, over 130 meters above sea level, rises to an additional 36 feet in height. The masonry is of white limestone extracted from the hill of Bonaria and has three closed sides that have a thickness of three meters, while the fourth side is open to the interior of the castle. The building was used for centuries as a fortification, home, warehouse, and even as a prison.  Together with her sister Elephant Tower is one of the few medieval buildings that were preserved in Cagliari or less intact. Both are open to visitors and offer an excellent view from the top of the city at 360 °.