The castle was built by Michael Komninos the Second and it is the most representative sample of the city's medieval character. It consists of the main fortress, two small outer ramparts and the Acropolis. It has a rectangular shape and every 25 m. there is a tower in a different shape. Its walls are 2.5 m. thick and 10 m. high. In the center of the hill you can see the ruins of a building that was probably the palace of Komninos family. On the left side of the entrance you can see the Acropolis (aka “Kastraki”, meaning “little castle” in Greek) which would be the last refuge for the besieged. Later on and for many years, this placed functioned as a prison. General Makrygiannis and his fellow fighters were imprisoned here.