Bunker 21 is a former military bunker located in Germany, identified as the remains of a Dreischartenstand (three-gun emplacement). The structure is part of Germany's extensive network of World War II fortifications. Dreischartenstände were typically designed to house anti-tank or artillery guns with fields of fire covering multiple directions.
The bunker's current state shows its historical military function, though specific details about its operational history or exact location within Germany remain limited in the available sources.