Tireless protector of the land, the castle of Ypati, capital of the Ainian people, was repeatedly besieged, over the ages, by many conquerors. The most important Byzantine monument of western Fthiotida, built on the remains of the Hellenistic acropolis of the ancient city of Ypati, was strengthened during the reign of Justinian (6th Cen. A.D.) and prospered in the 13th Cen. A.D. during the rule of Ioannis Aggelou Ist, the Duke Komninos. The legend of the beautiful daughter of the Byzantine lord, who was enticed and then abducted by the Pasha, is still considered part of its bastions, while folk tradition tells us that three spirits still guard the honour of the maiden from Patra who gave away the rosiness of her face to the oleanders surrounding the castle.