Dionysius I was responsible for the design of this powerful defensive system, completed in just six years (402-397 BC), in the difficult situation of yet another war against the Carthaginians.

The large rectangular building in the center of the architectural complex is the oldest and was initially directly connected to the first bastion that you encounter upon entering, of which today only a prow-shaped spur remains. Numerous alterations have taken place over time, up to the Byzantine era; to militarily innovate the castle, four towers, crenellated and square, barrier walls and above all new moats were added to the corners.

The result is a place equipped with a magnificent system of internal tunnels, accessible from the third moat, which was to be used in the event of a siege to move troops inside the castle without being noticed by the enemy. On the north side of the castle, there is also a monumental pincer door that gave access to the city.