Elysium

Elysium, known in Japan as Heaven (ヘブン), is a "perfect world" which orbits high over Terra (Earth in Japan). This is where The Master—the last human—lived out the most of his life. The Master lived on Elysium with Mega Man Trigger, Sera—the Mother Unit in charge of Elysium—and other units of the system. However, after The Master went down to Terra with Mega Man Trigger, and saw the people there—the Carbons—living happily, realized that it was better than living forever on the perfect, yet cold world of Elysium. The Master then asks Mega Man Trigger to end the Master System of Elysium, shutting down and preventing the eventual use of the Carbon Reinitialization Program.

History
At some point all of the original humans died or disappeared due to unknown circumstances and it is unknown who created or where the world of Elysium came from. The world of Elysium was not subject to aging, sickness, or hunger thanks to the advanced technology there. The Master—the sole remaining original human—lived out the most of his life in Elysium. He lived within the boundaries of Elysium for some time over 3,000 years. Eventually, The Master requested that Mega Man Trigger take him down to Terra. There he saw the the Carbons and the way they lived their lives, and he came to the conclusion that he never felt true happiness in the cold and sterile world of Elysium. Having left the perfect world of Elysium—unable to survive for long—the Master dies and leaves Mega Man with a final request—to destroy the Master System and shut down the Carbon Reinitialization Program before it is ever to be activated to wipe out all of the Carbons on Terra. The Master also gives Mega Man Trigger the only copy of his genetic code for safekeeping, calling it a good luck charm and telling Mega Man Trigger that so long as he had it with him that no would could harm or stop him.

The Library on Elysium contains copies of genetic information of the Ancients. Their genetic code was stored in the library so that they could eventually be resurrected after The Master died, and allow them to replace the artificial humans known as the Carbons.

The systems on Elysium were maintained by Sera and Yuna, who together made up Elysium's mother computer. Other android units were created, including Bureaucratic Models (known as Third-Class Purging Officers in Japan) like Mega Man Juno, and Purifier Units (known as First-Class Purging Officers in Japan) like Mega Man Trigger.

Elysium is essentially a space colony. It is completely spherical except for a single, spike-like protrusion. It is big enough that it can be seen from Terra like a very large moon. There is some speculation that Elysium is actually the moon, but Mega Man's memory of the Master shows the actual moon in the Terran sky, so Elysium would therefore be a separate entity from the moon.

In Rockman DASH: 5tsu no Shima no Daibouken!, Mega Man and Roll discover a group of enormous towers that have risen out of the sea. When Mega Man reaches the top of the tower in the center, he finds a broken elevator terminal with the obscured term "HEAVEN" written in ancient text. Additionally, Mega Man infers the damaged top of the tower indicates it may have once been even taller. This implies the tower might have once served as an orbital elevator for transport to Elysium that was eventually most likely destroyed, severing the link between Terra and Elysium directly.

Locations

 * The Shuttle Bay - A hangar where shuttle crafts can launch from and dock in Elysium. It is directly attached to the Defense Area and contains an elevator to reach the Residential Area.
 * The Defense Zone - A labyrinth-like zone connecting the Shuttle Bay to other areas. This zone is used as a layer of defense to keep out aggressors and intruders from entering further into Elysium. Many strong Reaverbots inhabit this area. There are control panels throughout the Defense Zone that allow you to control the gravity in a given area, either raising the gravity to make things heavier or lowering it to make everything appear to be lighter.
 * The Residential Zone - The Residentail Zone is made up of several islands out in what appears to be an endless sea, and the various islands are connected by different portals. There up to four portals on every island. An elevator in the center island connects to the Shuttle Bay. From here you can eventually get to the Master's House.
 * The Master's House - This is where the Master lived for the thousands of years that he was alive. Mega Man Trigger spent a lot of time here when he was in Elysium.
 * The Mother Zone - The area set aside for the two Mother Units Sera and Yuna who are also Elysium's mother computer. It is guarded with numerous powerful, boss-class Reaverbots. These Reaverbots are more powerful versions of the Reaverbots that guard the Keys to activate the Carbon Reinitialization Program.
 * The Library - The area where the genetic information of all of the Ancients is stored—all except for The Master's, which is in Mega Man Trigger's possession. The Master requested Mega Man Trigger to destroy the Library and shut down the Carbon Reinitialization Program, which caused his betrayal of the system. Sera waits here to fight Mega Man Trigger after having stolen the keys to the Carbon Reinitialization Program.

Notes and trivia

 * In the ending to Mega Man X5 where X doesn't remember Zero, X claims his dream is creating a place called Elysium (in the Japanese games, X refers to it as Heaven) where humans and Reploids can live in harmony. This is believed by some to clarify the X series' connection to the Legends series, although presently, there is no sign that X was involved with the Legends series' Elysium in any way. The Mega Man Zero chronology seemingly confirms that X's concept of Elysium eventually become Neo Arcadia and not the Elysium in Mega Man Legends.
 * Elysium appears to have a symbol that represents it It is usually in the form of a circle, sometimes a circle within a circle, that occasionally will have two points coming from the top and a longer point or a line that extends from the bottom. This can be seen reflected in the design of the keys to the Carbon Reinitialization Program, many designs and fixtures in Elysium or the Underground Ruins, and on Sera and Yuna's bodies and clothes along with Geetz and Gatz. The pattern is also seen on the top of Elysium that is covering a large part of the mass' surface.