The left hole in the foreground of the previous photo, which the author climbed though in 1993. The hole was made by breaking the 10 centimeter thick cement slab and cutting the reinforcing rods. The cut rods were then bent back away from the hole. The hole is 85 by 50 centimeters, large enough for people to easily climb through, and large enough to be readily visible on 1944 air photos, which it is not.