On March 17, 1941, President Franklin Roosevelt presided over the opening of the National Gallery of Art. Andrew Mellon made his fortune in oil, steel, shipbuilding, and construction, becoming one of the wealthiest people in America. During World War I, Mellon used his wealth to build a private art collection of old master paintings and sculptures. Appointed Secretary of the Treasury in 1921, he moved to Washington, D.C., and soon realized that America should have a national art museum like the ones in other great nations.