Dry Tortugas National Park

Dry Tortugas National Park, an area of 64,700 acres at the western end of the Florida Keys, is 70 miles west of Key West, Florida. Part of a mid-19th century chain of coastal defenses to protect the Straits of Florida, Fort Jefferson eventually grew to be the largest all-brick fortification in the New World. It served as a Union Army prison during the U.S. Civil War and as a federal prison for years afterward. The Dry Tortugas are a group of 10 mangrove-covered coral islets, or keys, one of which, Garden Key, is the site of the fort.