This is one of several old Spanish fortresses built to guard Havana's harbour from attacks by pirates who once terrorised the Caribbean, plundering galleons laden with Spanish gold, and attacks by other European powers. Construction on Castillo de la Real Fuerza began in 1558, and it is located in Plaza de Armes, opposite Palacio de los Capitanos Generales which housed the Spanish Admiralty and Cuba's old colonial rulers.
Despite the presence of these forts, Havana was still ransacked by pirates on several occasions, and was invaded by the British in the 1762 (it remained occupied for two years before being returned to the Spanish in a swap for Florida).