Castillo de la Real Fuerza
Havana, Cuba · built 1558
The Castillo de la Real Fuerza (Castle of the Royal Force) is a bastion fort on the western side of the harbour in Havana, Cuba, set back from the entrance, and bordering the Plaza de Armas. Originally built to defend Havana against attack by pirates, it was not strategically located, being too far inside the bay, and instead was adopted as the residence of the Governor of Havana. The fort is considered to be the oldest stone fort in the Americas, and was listed in 1982 as part of the UNESCO World Heritage Site of "Old Havana and its Fortifications".
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).