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 on a tactical level, while 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. Types Trench This type of bunker is a small concrete structure, partly dug into the g… (More on Bunker)