Nightmare Palace

The Nightmare Palace is a palace for Nightmare Steve, and a prison. Nightmare Steve made this so in his final attack when the trio, Sabre, Lucas, and Rainbow Steve appeared he would fight them (Sabre really - Lucas and Rainbow Steve were in cages). The Prisoners in this place were Positive Steve and Negative Steve, just so that they couldn't create Infinity Steve and kill Nightmare Steve, because Infinity Steve would be more powerful than his creator.