This is a defensive construction in a predominantly Neoclassical style. The first castle was built during the reign of Felipe II and it was redesigned between 1731-1775. It is one of the most representative examples of the major "fortified batteries" of the 18th century. It was used to defend the Ferrol tidal inlet and for land offensives. The castle has a system of protruding walls, covering the flanks of the lateral walls. It follows the academic model of its time - the Enlightenment - in this case, through the application of mathematics to the art of war. It has a geometric layout and stonework. It was designed by the military engineers Francisco Montaigú, Juan de la Ferriére and Juan Vergel. There are magnificent views from the castle, particularly for the tidal inlet and the A Palma castle. The building was recently acquired by Ferrol Council and will be renovated and refurbished for cultural use.