The Landkreuzer P. 1000 Ratte (En: Land Cruiser P.1000 'Rat') was to have massed over 1,000,000kg (1000 metric tonnes), required 3m wide tank threads, and may have protected a crew of at least 20 men with armour thickness reaching up to 360mm (>14 inches!) in front. Planned to be armed with two massive 280mm Navel Guns (Ok,l 11-inch guns are small for a battleship, but HUGE for a tank!!!) mounted in its massive turret; supported by a 128mm Anti-Tank gun Topping it off.... Twin 15mm (.60 Cal!) MG151 auto-cannons backed by eight 20mm Flak 38 Anti-Aircraft guns providing point defense.... By comparison, the modern day U.S. M1 Abrams MBT, uses a 120mm smooth-bore cannon (which is not a small gun in its own right lol); supported by 7.62mm and 12.7mm (.50Cal) machine guns.
In the Science Fiction world of Battle Tech and MechWarrior, there is a massive Clan OmniMech known as the Dire Wolf, known to those in the Inner Sphere as "Daishi" or the Great Death -- because it was such a huge weapon of war; watching it move would be like watching a battleship move cruise across the land slowly.... but so heavily armed and armoured, that a single Daishi could cut down anything in it's path with ease.
Until today, I never knew such a beast could even be dreamt of by real men..... unlike the Daishi, this tank is real. The P.1000 Ratte, without a doubt... would have been THE BIGGEST FREAKING TANK IN THE UNIVERSE, if it wasn't for the even more massive P.1500 Landkreuzer P 1500 Monster, I think I would have fallen out of my chair if the plans for the P.1500 had ever been completed -- a real Daishi for all intents and purposes!
Luckly the P.1000 Ratte never saw combat, and the plans for the P.1500 Monster, with its gigantic 800mm main gun, and supporting pair of 150mm howitzer guns was never finished.... Leaving the worlds biggest tank as the Panzerkampfwagen VIII Maus, of which only two were ever built and never saw combat with Germany forces. Although the "little" Maus only weighed 188 Tonnes, the P.1500 and P.1000 would have dwarfed it with one toe, had they ever been complted. Without the atom bomb coming online years later, these tanks would have been like the Death Stars of their day. No tank ever made by man kind would stand a chance against these machines if they had been fielded, you would need massive amounts of Artillery fire and carpet bombing from aircraft such as the B-17 Flying Fortress' and B-24 Liberators to even stand a chance at disabling ONE of these massive beasts.
When I saw what the Ratte would have looked like, my jaw hung open in shock and awe; I have always respected German Engineering ability, but now I am truly impressed....