The castle has being built in three architectural phases: Frankish, Byzantine and Turkish. It has a long and narrow floor plan and its length is nearly 170 m. It includes two enclosures, the interior where the garrison commander's tower-house is situated and the exterior that has a circular tower. The SE side of the castle towards Taygetos is rocky and inaccessible, while the castle wall downwards that fortified and protected Ano Chora, the palaces and other mansions above the Monastery of Pantanassa, ends in a cliff. The west side of the walls was guarded by a series of towers while the gates on this side were also securely protected. The second fortification enclosure was located a little lower and protected the main settlement.