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The Pisan Tower of St. Pancras was designed by the architect Giovanni Capula in 1305, to defend the northern entrance to the Castello quarter. Built on the highest point of the hill, at 130 metres above sea level, it provided a view of all the lands surrounding the town. In 1328 the open side was walled up by the Aragonese to transform it into storerooms and living quarters for officials. Starting from the 17th century, with the opening of the passage in the adjoining Palace of the Seziate, the tower lost its function as an entrance to the town to become a prison. It continued to be used as such up to the end of the 19th century. At the beginning of the 20th century the tower was restored to its original condition, with the reopening of the side facing Piazza Indipendenza, and the putting in place of the wooden landings. Recent restoration work has reinforced the structure and uncovered a part of the defensive works. Together with its twin, the Elephant Tower, it is one of the few medieval constructions in Cagliari that has come down to us practically intact. To be pointed out are different defensive solutions, such as the loopholes at different heights, the traces of the many defences of the underlying gate, which included two portcullises and three portals; finally, at the top there was a crown of corbels from which it was possible to drop things on attacking forces. The tower was surrounded by a wall called a barbican, beyond which was a moat. At different heights are Pisan coats-of-arms, while on the arched lintel of the gate on the opposite side there is an inscription in memory of the Pisan residents of the Castello at the time of its construction, of the builder who performed the work and the architect Giovanni Capula who designed it.