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 the main forts of the French Maginot Line, the strongest fortifications in existence at the time. The fully assembled gun weighed nearly 1,350 tonnes and could fire shells weighing 7 t to a range of 47 km (29 mi).