Preserve, northeastern Florida, U.S. Established in 1924, it is the 20-acre (8-hectare) site of the oldest masonry fort in the U.S., built by the Spanish (1672–96) to protect St. Augustine .
The fort played an important role in the Spanish-English struggle for the Southeast (1650–1750). In the 19th century it served as a U.S. military prison.