Venetian Castle or PalaioKastro
Paleokastro (literally meaning old castle ) lies in the eastern part of Ios island on the top of the islands highest hill. On taking the road back from Pirgos, you will end up on the beautiful, winding, stone paved road to Paleokastro. What looks like a scenically blessed place used to be a fortified area and was originally constructed to protect the local population from frequent pirate attacks.
The area is completely isolated now but the ruins allow us to have a glimpse of what life might have been like in the Middle Ages. One of the ruins that you can see is that of a Venetian Castle dated back to the 10th Century. It is made of marble surrounds a beautiful Byzantine chapel. It is about a 15minute walk from Psathi. Part of it is already fallen down from the cliffs into the sea but a few walls still remain.