Mystras Castle also called Villehardouin Castle, is the fortress that dominates the medieval city of Mystras in Greece. The castle was built by Guillaume II de Villehardouin. The fortress is located at an altitude of 621 m, consists of a double fence, was later transformed by the despots of Mistra and the Turks. The door of the internal enclosure is protected by a high square tower, of Byzantine origin. At the southern end of the plateau, a cistern and watchtower dominate the ruins. Geoffrey of Villehardouin (c. 1150 - c. 1213) was a French knight and historian who participated in and chronicled the Fourth Crusade. He is considered one of the most important historians of the time period, best known for writing the eyewitness account De la Conquête de Constantinople (On the Conquest of Constantinople), about the battle for Constantinople between the Christians of the West and the Christians of the East on 13 April 1204. The Conquest is the earliest French historical prose narrative that has survived to modern times. Ηis full title was: "Geoffroi of Villehardouin, Marshal of Champagne and of Romania".
