Bunker

A bunker is a defensive or protective fortified shelter designed to withstand blast, collapse, or other hazards. Bunkers are typically underground or partially buried structures built to protect occupants from artillery, airstrikes, or natural disasters, and can range from small dugouts to large command complexes.

Common types include military bunkers such as gun emplacements, observation posts, command centers, and storage bunkers; civilian bunkers such as storm shelters and fallout shelters; and special-purpose bunkers like munitions storage or data centers.

Construction and design: Most bunkers use reinforced concrete, steel, and earth to resist blast and collapse. Features may include blast doors, air filtration and overpressure systems, independent power and water supplies, ventilation ducts, decontamination areas, and secure communication lines. Entrance wells or protected access points are designed to limit exposure.

History and examples: The term bunker entered English in the 20th century, with widespread use in the Second World War and later during the Cold War for both military fortifications and civilian shelters. Notable examples include the Cheyenne Mountain Complex in the United States and the Greenbrier bunker in West Virginia, a Cold War-era shelter for members of the U.S. Congress.

In modern times, bunkers may be built for emergency preparedness or converted for other uses such as data centers or emergency operation centers, while concerns about safety, maintenance, and ventilation continue to shape their design and use.