   panzerkampfwagen viii maus ("mouse") was a german world war ii super-heavy tank completed in late 1944. it is the heaviest fully enclosed armoured fighting vehicle ever built. only two hulls and one turret were completed before the testing grounds were captured by the advancing soviet forces. these two prototypes &ndash; one with, one without turret &ndash; underwent trials in late 1944. the complete vehicle was  long,  wide and  high. weighing 200 metric tons, the maus's main armament was the krupp-designed 128&nbsp;mm kwk 44 l/55 gun (55 calibers long barrel), based on the 12.8 cm pak 44 anti-tank field artillery piece also used in the casemate-type jagdtiger tank destroyer, with an added coaxial 75&nbsp;mm gun. the 128&nbsp;mm gun was powerful enough to destroy all enemy armored fighting vehicles at close or medium ranges, and even some at ranges exceeding . the principal problem in the design of the maus was developing an engine which was powerful 
Superheavy_tanks Trial_and_research_tanks World_War_II_tanks_of_Germany