In the evening, when it is bathed in gold and silver light, St Peter's Castle rises likes a mirage over the peninsula. It was built in the 15C by the Knights of St John of Jerusalem, who made use of the ruins from a neighbouring mausoleum, as witnessed by the fragments of columns that appear in the impressive structure of this miraculously intact fortress. Nowadays, the castle is home to a somewhat gaudy Museum of Underwater Archaeology and to treasures, such as the wreck of a 10C Fatimid ship and its cargo of glassware.