High Quality Content by WIKIPEDIA articles! A bunker is a defensive military fortification designed to protect the inhabitants from falling bombs or other attacks. Bunkers are mostly below ground, compared to blockhouses which are mostly above ground. They were used extensively in World War I, World War II, and the Cold War for weapons facilities, command and control centers, and storage facilities (for example, in the event of nuclear war). Bunkers can also be used as protection from tornadoes.