Astypalea’s imposing castle was built by the Venetian Quirini family early in the 15th century. For the next 300 years, up to 4000 people lived within this ever-expanding precinct, sheltered from pirate attacks. Its last inhabitants left in 1956, after an earthquake caused the stone houses integrated into its walls to collapse. The only entrance is through a gateway that burrows beneath the Church of the Virgin of the Castle; the magical Church of Agios Georgios lies beyond.