With its panoramic view of the Aegean, Cretan and Ionian Seas, the medieval castle of Kythera once controlled the sea lanes of antiquity. Built atop an older site by Venetian conquerors in the 16th century, the castle saw economic prosperity as the small village of Hora developed.

Venetian officials and wealthy Greek noblemen built their mansions here. Inside the castle walls were the church of Panagia Myrtidiotissa, protector of the island, and the Palace of the Stewards, as it was called by the Venetians. These two buildings house the Kythera Historical Archives.

Prior to German occupation in World War II, the Fortezza (castle) still had permanent residents. Today only historical buildings and well-preserved remnants remain.