Yeah, these things mostly didn't happen. Thing is, in reality, they used up a lot of resources, and moving them around was a huge issue... also, with being so darn heavy, most of these monstrosities (Russians were also big into building giant thingies that went boom) tended to bury themselves, kill people that tried to operate them or just be very, very impractical. It's really not just about 'getting stuck', but being so heavy that anything beneath them squirms away, turns to mush or gets well crushed.
Here, have some more:
Russian Lebedenko / "Tsar" tank, ~1917, 12m high and really, really big wheels
http://www.landships.freeservers.com/tsar_tank_1to35scale_model.jpg
Oh, and that "Schwerer Gustav" - the second one was called "Dora", get this:
"The monster was so huge it took a team of 2,500 "volunteers" to lay track for it, and the train carrying and supporting it was 25 cars long, about a mile. "
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