American museum of art, part of the federally operated Smithsonian Institution system, located at the east end of the Mall, Washington, D.C. It was founded in 1937 when the financier and philanthropist Andrew W. Mellon (Mellon, Andrew W.) donated to the government a collection of paintings by European masters and a large sum of money to construct the gallery's Neoclassical building, which was designed by the architect John Russell Pope (Pope, John R.) and opened in 1941. That structure came to be known as the West Building after 1978, when it was connected by plaza and underground concourse to the new East Building, which was designed by I.M. Pei (Pei, I.M.) and Partners.

The National Gallery now houses a very extensive collection of European and American paintings, sculpture, decorative arts, and graphic works from the 12th to the 20th century. The museum has especially rich holdings of works by Italian Renaissance painters, as well as by Dutch and Spanish Baroque and French Rococo artists.