Adolf Hitler & staff inspect the Schwerer Gustav, The Largest Artillery Gun Ever Made, 1943
It required 250 men to maintain, move, & operate the behemoth. It also required 2 sets of train tracks, so to move it, the crew had to lay down a brand-new set of rails next to the existing track. It could take 3 months to get it into position. The barrel was good for about 40 shots, then had to be replaced.