An "orbital elevator" as its name implies, is a large elevator created with the intent of reaching orbit. Orbital elevators first appeared as part of the setting of Mega Man Zero and subsequently appeared in Mega Man Zero 3 and Mega Man X: Command Mission before becoming a major story element for the first time in Mega Man X8.
According to Mega Man X8, the first orbital elevator "Jakob" was constructed at Point Galapagos as part of the Jakob Project. It was new technology which would allow humans to begin migration to the Moon in effort to escape the endless Reploid rebellions. The orbital elevator's primary purpose is to transport equipment into space. From the top of the elevator, the Moon and the "Gateway" Space Station by means of teleportation or otherwise.
The director in charge of the orbital elevator and the Jakob Project is Lumine. However, Lumine would be kidnapped by Vile in an effort by Sigma to take control of the orbital elevator. As the orbital elevator is the route to space, Sigma planned to use the elevator to establish his new world on the Moon and in doing so, cutting off mankind's lifeline. Though, Sigma was ultimately defeated by the Maverick Hunters in an epic battle on the moon, the kidnapped Lumine revealed himself to have simply used Sigma to further his own plans. Lumine declared the new world was at hand, but he too would be defeated. With both Sigma and Lumine taken care of, the Maverick Hunters regained control of the orbital elevator and used it to descend back to Earth.
In Mega Man X: Command Mission, the orbital elevator "Babel" stands above Redips's Command Room and can be reached by teleporter. After passing through the "Super Strato-Terminal" the elevator leads to the "Strato Terminal" and "Teleport Room". From there, the ascending "Blue Earth Tunnel" provides a view of the Earth as it leads toward the final confrontation with the traitorous Redips. Like Lumine and Sigma before him, he too is ultimately defeated.
Mega Man Zero has the "Neo Arcadia Tower". From the Neo Arcadia Shrine, the Neo Arcadia Tower leads to the center of Neo Arcadia, Neo Arcadia Core. At an altitude of 36000km it connects to a stationary satellite containing the control room, Area X. The Neo Arcadia Tower is technically really a repaired elevator shaft that was once used in an orbital elevator for transportation between the Earth's surface and the Moon. The orbital elevator was destroyed in the Maverick Wars, however, and now this shaft is used to foil would-be infiltrators of Neo Arcadia. On the outside of the Neo Arcadia Tower, the words "orbital elevator shaft" can be read.
In Mega Man Zero 3, Area X-2 too is reachable by orbital elevator. From inside of this orbital elevator, many others can be seen. According to Remastered Tracks Rockman Zero IDEA and Remastered Tracks Rockman Zero TELOS, all the important places in Neo Arcadia such as Area X, Area X-2 and Yggdrasil are reachable by orbital elevator. However, Yggdrasil itself is noted as the exception to this.
An oribital elevator also appear in the 40th episode of Rockman.EXE Stream as a tourist attraction site visited by Lan and Mayl. However, it was hijacked by Neo WWW led by Tesla Magnets in order to drop a satellite onto Earth. Their plans were twarted by CF Lan and CF Mayl, who effortlessly delete Asteroid DesertMan and Asteroid FlashMan. With their plan failed once more, all members were arrested by the Net Police, putting an end to Neo WWW once and for all.