The castle most of it reconstructed by Alfonso V of Aragon has an irregularly trapezoidal plan and was defended by five large cylindrical towers, four covered with piperno and one with tuff, and crowned with merlons on brackets. The three towers on the side facing the ground, where the entrance is located, are the tower of San Giorgio, the tower of Mezzo (which collapsed at 11:30 am on 4 August 1876) and the tower of Guardia (from left to right), while the two on the side facing the sea they take the name of the tower dell'Oro and the tower of Beverello (from the left to the right). The castle is surrounded by a moat and the towers rise on large embankments, in which the texture of the stone blocks takes on complex designs, recalling Catalan Majorcan examples. '