Paleokastro is an ancient acropolis located on the top of hill above Mandraki
. The fortification was built around 4th century BC and its walls were sloping down to the seashore. Today the most preserved part is the top of the fortress, with thick walls of dark volcanic stones some of which are over 3 meters high at some places. The place offers panoramic view toward Mandraki and the Monastery of Panagia Spilliani.