The castle sits on a hill outside Kyparissia. According to mythology, it was built by Giants, hence its name. This was because the stones used for its construction are especially big, some at 4 by 1.64 meters, others 1.40 by 1.80 meters.

The first castle was built on the ancient acropolis by the Byzantines. In 1205, it was conquered by the Franks, who repaired and reinforced it. In the caste's four corners were towers, of which one remains to this day, named the tower of Justinian. The castle was taken by the Turks in 1460, and near the gate of the inner courtyard, which is now destroyed, are the remains of a square building that possibly was a mosque.

The castle was taken by the Greeks during the Greek Revolution, though it was almost destroyed. In 1970, a part of it was repaired, and a small amphitheatre was built, which holds shows and other artistic festivals every summer. Access is easy.