Castillo de San Marcos, on Matanzas Bay in St. Augustine, is the oldest masonry fort in the continental United States, built by Spain between 1672 and 1695 after repeated attacks on the settlement. Designed of coquina in a low, star-shaped form, it resisted major English sieges in 1702 and 1740 and was never taken by force. Control later passed among Spain, Great Britain, the United States, and the Confederacy through treaties and war. Its history also includes construction by Native laborers and enslaved Africans, the nearby refuge that led to Fort Mose, and later use by the U.S. as a prison for Native people before becoming a National Monument.

Photo: Wikipedia · Public domain

Photo: Wikipedia · Public domain

Photo: Wikipedia · Public domain

St. Augustine, Florida · USA