The Florida Keys are an archipelago that extend from the southeastern coast of Florida and westward past Key West into the Florida Strait, which separates the Gulf of Mexico from the Atlantic Ocean. The archipelago is made up of 1,700 islands. The last inhabited key is Key West, and the furthest keys from the mainland are the Tortugas chain, home to Dry Tortugas National Park. There on Garden Key sits the lighthouse in this photo on top of Fort Jefferson. The lighthouse actually predates the fort by over twenty years. The lighthouse construction was completed in 1826 and the fort began construction in 1846. The fort was never finished even though over 16 million bricks were used, and construction stopped in 1861 over fears that the island might not be able to support the weight that finishing the fort would require.