The Byzantine castle in the town of Agios Dimitrios was built in the 12th century by the Eudaimonogiannides of Monemvasia. It was a safe natural fortress built on the 216-meter high rock, in the Kakia Lagkada Canyon, 2 kilometers away from the northeastern shore. Because it was not visible from the sea, it protected the population from pirate raids. Its only access was from the southwestern side, through a six-meter high wall with battlements, which still partially stands today. On its northern and eastern side, the fortress is built on the cliff sides, with houses and churches. According to Gillian Ince, an archaeologist from the British Archaeological School who researched Paliochora, there were 23 churches and 70 houses within the fortress, most of which have collapsed.
Since its construction, the Agios Dimitrios fortress was an important residential and administrative center which reinforced the Eudaimonogiannis family’s domination. It remained active in the following years under the rule of the Venetian Venier feudal families, and then afterwards, when the island passed under the direct control of the Republic of Venice in 1363. In 1537, during the Third Ottoman-Venetian War, Hayreddin Barbarossa the chief admiral of the ottoman fleet besieged and sacked the Agios Dimitrios fortress. He killed many of its inhabitants and enslaved others to sell them at the slave markets in Constantinople and Smyrna. After the fortress’ destruction, the Venetians decided to abandon it. It hasn’t been inhabited since.