That is the monster my friend, P. 1500, there is a version which is exactly the same on wikipedia's article.
Wikipedia info here:
Conception
On 23 June 1942 the German Ministry of Armaments proposed a 1,000 tonne tank — the Landkreuzer P. 1000 Ratte. Adolf Hitler himself expressed interest in the project and go-ahead was granted. In December the same year, Krupp designed an even larger 1,500 tonne tank — the P 1500 Monster.
In early 1943, Albert Speer, the Minister for Armaments, cancelled the project.
[edit] Purpose
This "land cruiser" was planned as a self-propelled platform for the 80-cm K (E) guns also made by Krupp — the largest artillery weapons ever built. Their 7 tonne projectiles could be fired up to 37 km (23 miles) and were designed for use against heavily fortified targets.
[edit] Specification
The P 1500 would have dwarfed even the largest super-heavy tanks in development at the time — such as the German Panzer VIII Maus, the biggest built during the war. The Maus weighed 188 tonnes against the P 1500's proposed 1,500 tonnes. For comparison, the German heavy tank Tiger I weighed 57 tonnes.
The P 1500 was to have 250 mm frontal armour and be propelled by two or four diesel submarine engines. In addition to its main 80 cm gun, it would have been armed with two 15 cm sFH 18 heavy howitzers and multiple MG 151 autocannon.
[edit] Issues
Development of the Maus had highlighted significant practical problems associated with very large tanks — such as their destruction of roads, their inability to use bridges and the difficulty of strategic transportation by road or rail. The larger the tank, the bigger these problems became — to the point where they were insurmountable.
Propulsion had also proved problematic in the development of the Maus — the prototype had failed to meet its specified speed requirements which meant that even larger tanks such as the P 1500 were likely to be slow-moving and thus vulnerable to air attack.
