It is a fortress designed by the Italian architect Juan Bautista Antonelli and built by slaves with rocks extracted from the trenches in the last decades of the sixteenth century AD to defend the city of San Cristobal de la Havana. Because of economic problems and contradictions between the rulers of Cuba and Antonelli, construction work took 30 years and was not completed until the 17th century AD. Its floor is a polygon that adapts to the high rocks on which it is built facing the sea. Another interesting feature is the holes in the rear walls through which prisoners were fed sharks. This castle was the main defensive structure in the port of Havana until the completion of La Capna in 1774 AD.