Dry Tortugas National Park
Garden Key, Gulf of Mexico
Construction of Fort Jefferson began in 1846. The fort remained in United States control througout the Civil War, and served mainly to house prisoners, including Dr. Samuel Alexander Mudd who was sentenced to life in prison at Fort Jefferson for his role in the Lincoln assassination.
Fort Jefferson was part of the United State's comprehensive "Third System" of coastal defenses. Construction of these Third System forts began in 1816 with most being complete before the Civil War. These were large masonry forts that were to be constructed along the nation's coastline to protect important harbors, cities, interior waterways, and navy yards from seaborne attack.
Today the fort is preserved as as part of the Dry Tortugas National Park and a visit is well worthwhile. The site is accessible only by boat so planning is required! An entrance fee of $5 is required for visitors 17 and older. The fort is open during daylight hours year-round.