The City is an artificial intelligence responsible for curating the changes in the Children of the Vault.[4] It resides at the heart of the Dome, which itself is found in the heart of the Vault.[5]
History
The sentient futuristic City was founded by the Children at some point after they relocated their home base, the temporally-accelerated environment of the Vault, to the insides of the Wild Sentinel Factory in Ecuador. Its master A.I. resided in the City's center, inside the Dome.[5][6]
After the first generation of Children was defeated by the X-Men, the City produced a second generation and let them loose on the world. The anti-mutant organization called Orchis captured them at some point after that. Most of these Children were dissected and repurposed into potential weapons against Krakoa, the mutants' newly-created nation-state. Only Serafina managed to escape from Orchis, thanks to the X-Men. Upon learning the Children's fate from Serafina, the City decided that a third generation was to be produced.[7][1][8]
When Wolverine (Laura Kinney), Synch and Darwin invaded the Vault to evaluate the threat imposed by the Children's re-emergence, the City detected the trio and deployed the Children to exterminate them. During their confrontation, Aguja self-immolated, causing a huge explosion that destroyed a section of the City. The X-Men survived the blast and hid themselves while the City healed. One hundred years into the Vault's future, the City laid a trap and captured two X-Men: Darwin and Wolverine. Darwin was atomized by the City years later, with his genome being subsequently integrated into the Children to allow the creation of a fourth generation. Wolverine was freed from captivity by Synch prior to that, but sacrificed herself so Synch could escape the Vault to warn the rest of the X-Men about the Children's latest evolution.[8]
After Orchis forced Charles Xavier to psychically banish most of the mutants from Earth, the City left the Vault to unleash a psychic virus capable of bending people's wills to the Children's whims. Cable and Bishop, two of a handful of mutants who were able to resist Xavier's telepathic command and remained on Earth, discovered the Children's plan to enslave humanity and tricked Orchis into launching an attack on the City. In the ensuing chaos, Cable infected the City with his strain of the Techno-Organic Virus and, as the virus spread to the Children, threatened to let it consume them if they did not desist. Serafina, being the Voice of the City, agreed to Cable's terms and the City, as well as the Children, returned to the Vault.[9]