It is located on the seashore, east of Karystos, in order to protect the island from the enemies that arrived from the southeast sea. Built of marble and stone in the 13th century, the two-floor castle with the huge door was a creation of the Venetians and the Franks, who built most of the Greek castles. Its name is Arabic, meaning “seaside fortress”. The castle has loopholes and machicolations, from where pitch, hot water and oil were thrown to the enemies. It is also said that there was a 250 meters long tunnel, used for water supply, communication or emergency in case of a siege. Today it is used for exhibitions and is open to the public.