The Castle of Koskina in Ikaria, Eastern Aegean: In the centre of the island, in the inland road from Evdilos to Plagia, there is the ruined Castle of Koskina. Constructed on top of an abrupt mountain, this castle dates from the Byzantine times (10th century) and used to protect the locals from attacks of pirates and enemies, which is why it was built on such a steep mountain.
Most of the castle today is ruined and few parts of the walls can be seen. On top of the rock, there stands a small church dedicated to Saint George (Agios Georgios). Climbing up the castle is a tough experience, but the view from up there is breathtaking.