18. Fort Tilden: Breezy Point, New York
South of Brooklyn, on a fortified peninsula, one of many coastal U.S. military installations clings to the past on strange concrete platforms and structures. At one time, the United States kept anti-aircraft guns and surface-to-air missile systems in Fort Tilden, just in case. Today, the fort is long abandoned and the land designated as a national park. The National Park Service monitors the grounds where they’ve opted to keep the leftover parts of Fort Tilden.
17. Shivering Sands Maunsell Army Fort: England
Like some sort of crude, stationary At-At Walker from the Star Wars universe, the Shivering Sands Army Base rises from the water; buildings perched on four legs each. They seem like they could walk. Built as anti-aircraft stations during World War II, they pretty much just sit there as silent sentinels of a bygone time put out of work by the end of the war. These structures could make a good place to film a dystopian movie about a world covered in water.