The Territorial Legislature of Utah created Fillmore City and Millard County and selected Pahvant Valley as the capitol site on October 29, 1851. Governor Brigham Young chose this spot. Construction began in 1852, with Truman O. Angell as architect and Anson Call as supervisor. This south wing was used by the fifth Territorial Legislature on October 10, 1855. In 1856 the seat of government was moved to Salt Lake City. The building was later used as a courthouse and county headquarters, restored in 1928, and dedicated as a state museum on July 24, 1930.