The Venetian Castle of Ios: Ios' Venetian Castle is also called Paleokastro, which translates into "old castle". It lies in the eastern part of Ios on the top of the island's highest hill.
After taking the road back from Pyrgos, you will end up on the beautiful, winding, stone-paved road. 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 raids.
The area is completely isolated now but the ruins allow visitors 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 dating back to the 10th century AD. It is made of marble and surrounds a beautiful Byzantine chapel. It is about a 15-minute walk from Psathi. Part of it is already fallen down from the cliffs into the sea but a few walls still remain.