This is original ammunition railway wagons for Schwerer Gustav, displayed in czech republic : r/ww2

Schwerer Gustav - Wikipedia

Biggest Gun Ever Made - 800mm Schwerer Gustav Railroad Gun

File:Schwerer Gustav projectile 2.jpg - Wikipedia

Why It failed?:The Schwerer Gustav, Johnny OTGS World Wikia

800mm APCBC Shell [Schwerer Gustav] (5LLJL529X) by HappyBattleSheep

Could we make a round for the 80cm Gustav Gun with a nuclear warhead, and how big could the explosion be? - Quora

Artillery shell round hi-res stock photography and images - Alamy

Ammunition Size Comparison (3D)

TankHistoria - Schwerer Gustav was a German 80-centimetre (31.5 in) railway gun. It was developed in the late 1930s by Krupp in Rügenwalde as siege artillery for the explicit purpose of destroying

Schwerer Gustav, largest rail cannon in the world