Predating the city of Cienfuegos by nearly a century, this fort, to the west of the mouth of Bahía de Cienfuegos, was designed by José Tontete in 1738 and completed in 1745. At the time it was the third most important fortress in Cuba, after those of Havana and Santiago de Cuba.

　　Extensive renovation in 2010 gave the castle the makeover it sorely needed. In addition to a cracking view of the bay, the castle has a basic museum spread over three levels showcasing its history in a detailed timeline along with old cannons, armaments and engravings. Captions are in Spanish.

　　Passenger ferries to and from the castle ply the waters to Cienfuegos (CUC$1, 50 minutes) at least daily, leaving Cienfuegos at 8am and 1pm and returning at 10am and 3pm. Another ferry leaves every 30 minutes or so to a landing just below the Hotel Pasacaballo in Rancho Luna (CUC$0.50, five minutes).