Battery Oldenburg is a German artillery battery, built during World War Two as part of the Atlantic Wall, and situated east of Calais. The battery began in 1940 with artillery guns in an open emplacement. The Organisation Todt built casemates around two 240mm guns during the war. Both casemates or Turms (towers) are 35 meters long and 15 meters high, positioned in a slight offset from each other to gain a broader range with both guns. Turm East and Turm West housed guns of Russian origin that were captured by the German army during World War One and re-chambered by Krupp from 255mm to 240mm.