On a remote island hours away from Key West, Florida, lies the largest masonry structure in the Americas: Fort Jefferson. Built with 16 million bricks, but never finished, the fort served as a prison during Civil War. In 1935, President Franklin D. Roosevelt, upon visiting the island, named it a National Monument, and in 1992 it became part of Dry Tortugas National Park. Besides serving as a safe haven for the most preserved coral reef in the United States, the set of islands that comprise the national park also protect countless marine animals and bird species. However, the true treasure of this amazing place was noted by one of its most famous prisoners, Dr. Samuel Mudd, who once said that the the only escape from the hell of this prison was gazing at the night skies. Today, Dry Tortugas National Park is the darkest spot on USA's East Coast.