|The Castillo de San Marcos site is the oldest masonry fort in the United States. It is located in the city of St. Augustine, Florida. Construction was begun in 1672 by the Spanish when Florida was a Spanish territory. During the twenty year period of British possession from 1763 until 1784, the fort was renamed Fort St. Mark, and after Florida became a U.S. territory in 1821 the fort was again renamed Fort Marion, in honor of revolutionary war hero Francis Marion. In 1942 the original name, Castillo de San Marcos, was restored by Congress. The site was never taken by force despite multiple periods of attack.