The castle of Koskina was the most important and dominant of all the fortresses of Ikaria. It played the most important role in the defense of Ikaria and for that reason it is known as the Castle of Ikaria.
It is said that it was inaccessible and unpregnable and that it was one of the basic defense positions of Byzantine times. Undoubtedly, its natural location, on a mountain peak, overlooking the entire area (both North and South sides of Ikaria to the sea), together with its sturdy structure and the courage of the Ikarian fighters, kept it unbeatable for ages. Within the castle there is a little chapel from that period dedicated to St. George.
The visitor can get to the castle via the central mountain road from Evdilos to Agios Kirikos and then through an old mountain path (one hour walk) above Kossikia village.