Hidden Palace Zone is a mysterious zone which was originally removed late in the development of Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis. It is an underground cavern full of water featuring sparkling gems and rocky regal structures, possibly ruins of some ancient civilization. A similar stage with the same name later appeared officially in the game Sonic & Knuckles, serving as its inspiration. It was among the last levels deleted from the game.