Schwerer Gustav

Weight 1,350 tonnes
Length 47.3 metres
Barrel length 32.5 metres
Crew 250 to assemble the gun in 3 days (54 hours), 2,500 to lay track and dig embankments. 2 Flak battalions to protect the gun from air attack.
Caliber 80 centimetres (31 in)
Rate of fire 1 round every 30 to 45 minutes or typically 14 rounds a day
Effective firing range about 39,000 metres