I photographed this CPBC (Concrete Piercing, Ballistic Capped) 800mm shell and Casing for the German Gustav Rail Gun at the Ordnance Facility; Fort Lee
The shell weighed 7.1 metric tons, and could punch through 7 meters of rebar-reinforced concrete and up to 10 meters of plain concrete before exploding deep within the target.
By the way, this thing is BIG.