HKB Heuqueville is a dangerous World War II German coastal defense and Atlantikwall (the Atlantic Wall) fire control site that now precariously overhangs eroding 100-meter chalk cliffs north of Le Havre in Normandy, France. HKB stands for Heeres Küsten Batterie or Army Coastal Battery. It was built by the Nazi during WW2 during the German occupation of France to spot allied shipping movements in the English Channel and direct artillery fire from neighboring gun emplacements. The complex features personnel shelters, ammunition stores, remnants of gun rings, and a massive Fire Control Post complete with plotting rooms and observation chambers. Access is extremely hazardous and forbidden by municipal orders due to the permanent risk of sudden cliff collapses and landslides - which would not stop me!
Also seen
HERE at Virtual Globetrotting.