The Eurialo castle is a fine example of Greek military architecture. It was commissioned by the tyrant Dionysius I, built on the highest point of the town in 400/300 BC to protect it from possible military enemy attacks. The structure reflects its purpose: the entrance was protected by three moats, beyond them there was a fence and the keep defended by five large towers. The front door of the castle was open on a thick wall 5 meters wide. Moreover, there were many useful elements to defend it from the attacks; for example a tunnel system that allowed the troops to move easily within the fort or the door that allowed to surround those who entered.