The skyscraper was built by the Union Trust Company, founded in Detroit in 1890 by Senator James McMillan, and Dexter M. Ferry, along with investments from Russell A. Alger, Col. Frank J. Hecker, and Christian H. Buhl. During World War II, the Guardian Building served as the U.S. Army Command Center for war time production. The Guardian served various tenants as an office building in downtown Detroit. In 1982 it became the headquarters of Michigan Consolidated Gas Company ("MichCon") subsequent to the divestiture of MichCon by ANR Company in 1981. Under the leadership of President and COO Stephen E. Ewing, MichCon restored the lobby and vaulted ceilings on the first floor in 1986. It would stay MichCon's later to be called MCN Energy Group headquarters until the merger of MCN with DTE Energy in 2001. It was sold by DTE to a local real estate developer, the Sterling Group, in 2002.