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Roger the Norman originally built this castle in the 12th century over the ruins of a Byzantine structure. Later, Frederick II of Swabia built over the existing castle, incorporating it into his design and leaving intact the two towers of the Norman structure that still stand. The bastions, with corner towers overhanging the moat, were added in the 16th century during Aragonese rule. Excavation is ongoing and the largely sparse interior is used for occasional art and sculpture exhibitions.