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
Formerly Utopia, San Francisco Bay, California; Genosha; Xavier Institute, Salem Center, Westchester County, New York; Imperial Palace, Chandilar, Shiar Empire; Columbia University, Manhattan, New York City, New York