Fort Zachary Taylor, in Key West, Florida has provided harbor defense in four wars: The Civil War, Spanish-American War, World War I, and World War II. Construction of the fort began in 1845 with various expansions and modernizations of the fort and weapons occurring until the Army deactivated it in 1947. In the lead up to the Spanish-American War, batteries and new weapons were added. During World War II, 5-inch anti-aircraft guns were positioned within the fort. With the end of World War II, the harbor defense system was considered obsolete, and the Army transferred the property to the Navy.
The Formerly Used Defense site comprises 51.32 acres that were deeded to the State of Florida in 1979. Fort Zachary Taylor is a federally designated National Historic Landmark, and the Florida Division of Recreation and Parks preserves the fort and operates the Fort Zachary Taylor Historic State Park.