The main sight is the 13th-century Frankish castle, built at the top of the hill, with its highest point rising above the town. It consists of a triangular circuit wall, over 110 m in the long sides and ca. 40 m at its base, and a central structure which served as the barons' residence, built above the castle cistern. The castle was repaired by Kolokotronis, who erected a small church dedicated to the Virgin Mary, and built his house outside the walls.
Source: wikipedia.org