Base
The Xavier Institute, Salem Center, Westchester County, New York State, (former) The Alley (beneath Manhattans surface), X-Factor Is sentient starship
(current) Professor Charles Xaviers Institute for Higher Learning, Salem Center, Westchester County, New York (former) Muir Isle, Scotland,; a loft in Soho, Manhattan, Ust-Ordynski Collective, Lake Baikal, Siberia, U.S.S.R., X-Men Headquarters in Austra