[Schwerer Gustav/Dora]: The names of two German 80 cm ultra-heavy railway guns. They were developed in the late 1930s by Krupp as siege artillery for the explicit purpose of destroying the main forts of the French Maginot Line, the strongest fortifications then in existence. The twin guns weighed nearly 1,480 tons, and could fire shells weighing seven tons to a range of 29 mi. The guns were designed in preparation for the Battle of France, but were not ready for action when the battle began, and in any case the Wehrmacht's Blitzkrieg offensive through Belgium rapidly outflanked and isolated the Maginot Line's World War I-era static defenses, forcing them to surrender uneventfully and making their destruction unnecessary. Gustav was later used in the Soviet Union at the siege of Sevastopol during Operation Barbarossa, with good effect, including destroying a munitions depot buried in the bedrock under a bay. They were moved to Leningrad, and may have been intended to be used in the Warsaw Uprising like other German heavy siege pieces, but the rebellion was crushed before it could be prepared to fire. Gustav was later captured by US troops and cut up, whilst Dora was destroyed near the end of the war to avoid capture by the Red Army.

It took up to a crew of 250 men and 3 days to assemble, and up to a crew of 2,500 men to lay the tracks and dig embankments. Prettier and more intimidating than a modern M1A1 Abrams tank in my opinion.