Bunker

A bunker is a defensive military fortification. Bunkers are mostly below ground, compared to blockhouses which are mostly above ground. They were used extensively in World War I and World War II. During the Cold War, massive bunker complexes were built to house both strategic (command & control) infrastructure as well as government personnel and stores for the event of a nuclear war. During that time, bunkers became a part of American culture with people building backyard fallout shelters, though these were not intended to protect against direct attacks as bunkers normally would.