Fort Jefferson

Fort Jefferson is a hexagonal sea fort on Garden Key in the Dry Tortugas, Florida, built from more than 16 million bricks across roughly 16 acres. The two-story structure forms a ring of casemates around a central parade ground, surrounded by thick walls and bastions.

Construction began in 1847 and lasted over three decades but remained unfinished as advances in artillery made the brick walls vulnerable. During the Civil War the fort served as a prison for captured soldiers and later for civilian inmates.

The name honors Thomas Jefferson, the third president of the United States, whose vision for coastal defense shaped this fortification. Today the structure serves as a museum where visitors walk through empty casemates and see the cells that once held prisoners.

Access is by ferry or seaplane from Key West, with the boat trip taking around 2.5 hours. The park has no shops or restaurants, so visitors should bring water, food, and sun protection.

The fort never fired a shot in battle and remained unfinished at war's end, its brick walls already outdated. Today it hosts thousands of seabirds that nest on the walls and flutter through the empty passageways.

Location: Monroe County

Inception: 1847

Floors above the ground: 2

Part of: Dry Tortugas National Park

Website: https://nps.gov/drto/learn/historyculture/fort-jefferson.htm

GPS coordinates: 24.62778,-82.87306

Latest update: December 4, 2025 23:01