The National Gallery of Art is an art museum in Washington, D.C., United States, located on the National Mall, between 3rd and 9th Streets, at Constitution Avenue NW. Open to the public and free of charge, the museum was privately established in 1937 for the American people by a joint resolution of the United States Congress. Andrew W. Mellon donated a substantial art collection and funds for construction. The core collection includes major works of art donated by Paul Mellon, Ailsa Mellon Bruce, Lessing J. Rosenwald, Samuel Henry Kress, Rush Harrison Kress, Peter Arrell Browne Widener, Joseph E. Widener, and Chester Dale. The Gallery's collection of paintings, drawings, prints, photographs, sculpture, medals, and decorative arts traces the development of Western art from the Middle Ages to the present, including the only painting by Leonardo da Vinci in the Americas and the largest mobile created by Alexander Calder.

An art museum or art gallery is a building or space for the display of art, usually from the museum's own collection. It might be in public or private ownership, be accessible to all, or have restrictions in place. Although primarily concerned with visual art, art museums are often used as a venue for other cultural exchanges and artistic activities, such as lectures, jewelry, performance arts, music concerts, or poetry readings. Art museums also frequently host themed temporary exhibitions, which often include items on loan from other collections.