Avalon
The floating headquarters for the mutant group, the Acolytes, which has since been destroyed.
History
Avalon was salvaged from parts of Cable's ship Graymalkin. X-Force deceptively destroyed Graymalkin after S.H.I.E.L.D. attempted to invade it and use it for their own purposes, but most of its critical parts remained cloaked or within X-Force's possession.
The mutant messiah Magneto later acquired several parts, eventually building the mutant sanctuary Avalon, a haven for mutants that floated in space. The base became headquarters to Magneto's group the Acolytes, including high ranking member Exodus. While Exodus tried to recruit Magneto's former students from the New Mutants (who were now part of the Cable-led militant group X-Force) to stay in Avalon, Cable returned to his former ship and tried to destroy it.
Unfortunately, the ship was later destroyed when Onslaught attacked the base leading to it crash landing into unknown parts of Australia. Many members of the Acolytes died, but several--including Exodus, Scanner, Frenzy, the Kleinstock brothers, and Unuscione--were able to survive.
Ironically, Avalon's parts once again came into the possession of Cable, who used the remnants of Avalon to build his isolated island nation Providence.
Alternate Realities
Earth 295: Age of Apocalypse

In this reality, Avalon was the last refuge of Humans and Mutants who wanted to escape Apocalypse´s tyranny. The place was a real paradise full of life where humans and mutants coexisted in peace and harmony. The placed was ruled by Destiny and Cypher (her adoptive son).
It was located hidden at the Antarctica, ressembled Savage Land of main reality but with different topography, this site was one of the only places in earth free from interference of Apocalypse until Shadow King mindcontrolled every inhabitant making them kill each other and burn the villages. Thus it was abandoned.
In order to reach the Sanctuary, people must get passage from the tribe Ghost Dance in the "Infernal Gallop", then Mystique ferried refugees from an Antarctic station to the shores of Avalon. Then the travelers would be conduced into Avalon by Cain (a massive monk).
Infernal Gallop
For years after the arrival of Apocalypse, humans and mutants has been seeking somewhere to hide. This place took form on the heavenly Avalon, a place to live in harmony without the worries of the genetic war. Directed by Destiny, a powerful mutant with clairvoyance powers, and her son Doug, with the ability of handle of all kind of languages. This haven prove to be a safe homeland to mutants and humans alike.
The path to reach Avalon is barely known for most people, all that they know for sure is its harshness and secrecy.
First stage - Ghost Dance - John Proudstar became the spiritual leader of an anti-Apocalypse religous cult, he permitted safe passage to Infernal Gallop to trustworthy survivors.

When Nightcrawlertried to get entrance to the Infernal Gallop, Proudstar stopped him and questioned about his mother´s real intentions, Nightcrawler enraged chopped off one of his fingers using his teleportation, forcing Proudstar to give him access to the Gallop. Later the Madri, servants of Apocalypse, reached and attacked Ghost Dance killing all members of the cult, including Proudstar. They were betrayed byDanielle Moonstara sadistic cover agent of Apocalypse.
Second stage - Atlantic Ocean - The people admitted must crossed the ocean to Antartica paying expensive tariff. Mystiquewas working on the Infernal Gallop as a Ferrywoman. But her actions got her to believe that she was not worthy to enter Avalon. Thousands of people died trying to pass the ocean. This stage was one of the hardest on the journey, since the passangers must face countles threats, as pirates (Callisto), hunger and diseases.

Third stage - Cain- When the passsangers were able to reach Antartica, they must cross an underground river guided by a cloaked ferryman and finally received by a massive monk (Cain) who guided them through a long road. At the end of the road was the promised land.
Fourth stage - Avalon - After having crossed many hardships the survivors were few, but the people that made it were welcomed in Avalon by Destiny in person.
Members: John Proudstar, Mystique, Cain, Destiny and her son Dough Ramsey.
In Other Media
Video Games

- Avalon is featured in X-Men: Mutant Apocalypse, where Magneto uses it as his base of operations. He plans to destroy Genosha from Avalon, but the station is infiltrated by the X-Men, who manage to defeat both Magneto and Exodus.
- Avalon is featured as Magneto's stage in the Japanese fighting game X-Men: Children of the Atom. The game's final battle is fought there, and Avalon is destroyed after Magneto is defeated.
- Avalon is featured as a stage in X-Men 2: Clone Wars.