Some TMNT stuff really isn't for little kids.

Shredder's underground headquarters appear in the early issues of Teenage Mutant Ninja Turtles Adventures by Archie Comics. They are located beneath New York City.

After Shredder has been defeated in the The Final Conflict, the band Merciless Slaughter later uses the place for practicing as seen in Mondo Metal. It is here that Mondo is accidentally mutated into a gecko.

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