German railway Mörser Karl, .c 600(mm) Produced 1939 for the campaign vs France at Rhine Metal Company. By the Time it was completed France already has surrendered, so it was used against Russia (Sevastopol, Brest-Litovsk and Warsaw)
Propelled by an Daimler-Benz MB 507 12 cylinder liquid-cooled diesel engine providing a maximum speed of 10 km/h
Alternate Equipment made this Monster a 540mm Morser with longer Range than the 640mm one.