Atlantinopolis is a location that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. It is a city from the planet Moebius, located on the Sunken Island. Atlantinopolis is an alternate version of Echidnaopolis, but is uninhabited except for O'Nux.
The Atlantinopolis was threatened with destruction by Dr. Robotnik and Evil Sonic when they tried to steal its Anarchy Beryl, but thanks to the Knothole Freedom Fighters and Knuckles the Echidna, the city was saved. It was presumably either conquered or destroyed by King Scourge during his takeover of Moebius when he battled O'Nux.
- Atlantinopolis is named after Atlantis, a legendary sunken city.