In Comics
Superman's Pal, Jimmy Olsen #134 - The Mountain of Judgement
Giant-Size X-Men #1 - Deadly Genesis
Base
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(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