Koopacropolis

The Koopacropolis is a platform situated at the top of a large hill, it was also used as the hideout of King Koopa in The Super Mario Bros. Super Show! episode "The Fire of Hercufleas / The Marios Fight Back".

Not much of the Koopacropolis is actually seen, though from little of it was seen, it seems to be almost noting more than a flat platform on a mountain. After he was defeated, King Koopa abandoned the Koopacropolis.