Schwerer Gustav - The Greatest, And Most Useless Gun Ever Put Into

Gustav fired a total of 48 shells at Sevastopol, most of which were aimed at Soviet fortresses. Berlin threw away more 1,000 tons of steel for 48 shots.

Schwerer Gustav: Largest Gun Mankind Has Ever Built

Which modern gun can outmatch the WW2 800mm Schwerer Gustav? - Quora

Schwerer Gustav - Wikipedia

The UnMuseum: Schwerer Gustav - World's Biggest Gun

The UnMuseum: Schwerer Gustav - World's Biggest Gun

What are the most ridiculous guns ever invented? - Quora

Schwerer Gustav: Largest Gun Mankind Has Ever Built

Schwerer Gustav: The World's Biggest Gun Ever Built

warfare - Long Range Big Guns: An extreme bombardment ship - Worldbuilding Stack Exchange