Echidnaopolis is a location that appears in the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics. The only city on Angel Island, it was founded centuries ago by travelers from Albion in the country of Downunda.
They remained there for many years, until the city was threatened by the White Comet. Knuckles' scientist ancestors Jordann and his wife Kayla-La (Dimitri and Edmund's great-great-grandparents) used the energies of twelve Chaos Emeralds to lift the city and part of the surrounding landscape into the sky, leading to the creation of Floating Island, which was later renamed after Dimitri and Edmund's mother, Angel-La. Part of the population left before the city was raised, wanting to go back to Albion (see Lost Tribe below).
The society on Echidnaopolis suffered another, much larger schism of its population over six hundred years ago, which stemmed from the decision of the Echidna Council (particularly Menthor, the High Councilor at the time) to deny Dimitri and Edmund's plan to restore Angel Island to its original site on Mobius. When Dimitri took matters into his own hand and attempted to use the Chaos Syphon to drain the power of the Chaos Emeralds so the Island would slowly descend onto Mobius, the power was sapped into him. Despite the immense power he obtained, he was defeated by his brother Edmund, with assistance from the fire ants. Because the use of technology nearly resulted in the destruction of their civilization, the Echidna Council then deemed technology banned. However, Dimitri's son, Menniker decided to follow in his father's footsteps. He created the Dark Legion-a technocratic group of Echidnas loyal to Dimitri's cause of restoring the Island to Mobius, as well as maintaining technology in their society-which became a warring faction with the rest of the society. Since then, both the Dark Legion and the rest of the Echidnas in Echidnaopolis have been in conflict. Recently however, Dimitri attempted to end the long-standing grudge between the two societies and bring them together. This seemingly failed when Lien-Da took control of the Dark Legion.
Echidnaopolis itself was destroyed when the Dingoes joined forces with Dr. Robotnik, took over, and build Cavem Canus on top of its remains. Overwhelming the Echidnas and forcing them into concentration camps as well as killing off ninety percent of them. The few survivors were later liberated by the Chaotix and relocated to a village, but with most of the Brotherhood gone they were ill-equipped to defend themselves. Locke the Echidna, Guardian and father of Knuckles, defended them briefly before turning the position over to Dr. Finitevus, which allowed him to go off in search of his predecessors. Finitevus and his Destructix minions defended the former residents of Echidnaopolis briefly, until the new Enerjak came to power-he then transported them to Albion with the rest of the Echidnas in hopes of rebuilding their ravaged species.
Mobius: 25 Years Later
Echidnaopolis is the capital city of Republic of Angel Island and the home of Knuckles, Julie-Su, Lara-Su, Lien-Da, Dimitri, Rutan, Cobar, Mace, Espio, Salma, Juanita, Riki-Le, and Abby in the unaltered timeline of Light Mobius. (StH: #131, #132, #133, #134, #135, #136, #137, #138, #139, #140, #141, #142, #143, #144)