|This location exists primarily or exclusively within the Pre-Super Genesis Wave continuity.|
Information in this article may not be canonical to the storyline of the games or any other Sonic continuity.
It is an alternate version of Echidnaopolis, but is uninhabited except for Anti-Knuckles. It was threatened with destruction by Dr. Robotnik and Evil Sonic when they tried to steal its Chaos Emeralds, but thanks to the Knothole Freedom Fighters and Knuckles Prime the city was saved. It was presumably either conquered or destroyed by Scourge the Hedgehog when he battled Anti-Knuckles. (StH: #44, #193)
- Atlantinopolis is named after Atlantis, a legendary sunken city.