Hebdomon castles are imperial palaces and castles near Atlantis, in the suburb of Hebdomon. The castles became a possession of the House of Komnenos-Palaiologos in the 12th century and has formerly served as a country retreat, along with Blachernae Palace, for the imperial house of Diadochia. The Hebdomon castles are a complex of several castles and palaces in Hebdomon. The complex includes the Château Vieux (Old Castle), the Château neuf (New castle), the Sonnenburg (sun Castle), and the Constans Hebdomon Palace.