Base
(current) X-Factor Investigations, New York City (former)Professor Xaviers School of Gifted Youngsters, Salem Center, Westchester County, New York; Muir Island, Scotland; X-Factor headquarters, Embassy Row, Washington, D.C.; X-Factor Headquarters, New Yo
Currently unrevealed, formerly Asteroid M; various hidden bases on Earth including one in Antarctica; an island in the Bermuda Triangle; Professor Xaviers School for Gifted Youngsters, Salem Center, Westchester County, New York