Landkreuzer P . 1500 Monster The Landkreuzer P . 1500 Monster was a Prototype of an ultraheavy tank , designed by Krupp that would serve as a platform for artillery vehicle Schwerer Gustav . The project began in 1942 but was canceled by Albert Speer . If completed the tank would be bigger than the Panzer VIII Maus ( The largest tank ever built and even larger than Landkreuzer P . 1000 Ratte which was also was never completed ) . History . German developers had been designing since 1942 , the process - heavy tanks . Among other things , this was a planning of the P - 1000 " Ratte " out , one 1 , 000 - ton tank , which surpassed anything seen before . Hitler , who was fond of oversized projects , approved the development of this superheavy tank . The company Krupp thereafter began a plan to create an even bigger , heavier , more massive tanks . The P - 1500 , which was later known under the code name " Monster " . These plans were designed with special intentions for Hitler and he encouraged the ambitions of the defense industry , such " monsters " . Just as the predecessor of the P - 1500 , the project was the beginning of 1943 Minister of Defence Albert Speer adjusted , he saw for such oversized Land Cruiser no use in a war of aggression . There are no Blueprints or detailed drawings of the famous P - 1500 , which survived the war . All images and designs are purely speculative and therefore give only possible construction . Description . Arming . The P - 1500 was primarily designed as a mobile variant of the Dora and Gustav - guns . These huge artillery gun were the largest cannons ever built in history , and required 56 hours for pure assembly . Total lasted a full deployment of the gun five or six weeks because hauled ammunition , shelter dug flak had to be built , etc . But these characteristics were against the use of the gun in a tank . In addition , should the P - 1500 with two guns of caliber 300 mm at the rear will be equipped to be protected against attacks . Weight and power . The projected weight of the P - 1500 exceeded all standards . But his main armament would have weighed almost 500 tons . There was also a strong armor and a consequence of the armament size . Yet this enormous weight would have caused big problems because the tank would have been unable to transport . Since eight Daimler - Benz engines were too weak , the developers saw four MAN Submarine - Engines ( 6500 HP ) as a drive before . Nevertheless , the tank would have only a speed of about 20 km per hour can reach . In addition , a crew of 100 men would have been necessary . Use in war . If the P - 1500 had been completed , the Nazis would had found its use in a tactical war of aggression is not a viable use . In the attack it would have made the enemy with its immense firepower and thick armor , a huge obstacle , but it would have been easy to bypass the tank because of its very limited maneuverability , and so attacking from behind . would have only as artillery in the rear of the P - 1500 can be used , as its Dora - gun with 50 mile range was perfect for the destruction of strong defense installations . Moreover , the size , weight and width of the war leadership presented an almost impossible problem to solve , since the P - 1500 had neither the train , flat bed , yet other logistics facilities can be transported . Moreover , it was impossible for it to cross bridges , villages and tunnels . How much fuel would have such a " monster " used is not known . However , it is assumed that Germany - particularly against the war - these amounts of diesel it could not afford .