The fortress, also called the castle, was erected by King Philip V of Spain (1683-1746) in 1742 to protect the bay from pirates who prowled the Caribbean coast in those days.

They used it as refuge at landfall, on their way to the city of Cienfuegos (founded on April 22, 1819, by French colonists, bordering the Bay of Jagua), seeking collect water, food and other supplies.

[citation needed] The fort is built in solid limestone, has several floors, a well, a watch tower and a moat that was never flooded.

Since the coastal city of Cienfuegos was built at the end of the 1810s; its harbor, guarded by the fortress, became one of the most important centers of commerce in the central part of the "Island of Cuba" during that period of the colony, and to this day remains one essential port on the country's economy.

This is the case of banknotes, "Exchange Certificate" of 10 pesos, Letters A (reds) and B (greens), issued during the 1980s, and taken out of circulation, "as special legal tender" in the late 1980s and early 1990s; in its back, these banknotes, have a beautiful and attractive design of that "Castle" (a great drawing) to perpetuate forever, in the Numismatics history of the Big Island of the Antilles.