The National Air and Space Museum (NASM) of the Smithsonian Institution is a museum in Washington, D.C., United States, and is the most popular of the Smithsonian museums. It maintains the largest collection of aircraft and spacecraft in the world. It is also a vital center for research into the history, science, and technology of aviation and spaceflight, as well as planetary science and terrestrial geology and geophysics. Almost all space and aircraft on display are originals or backup crafts to the originals.

The National Air and Space Museum is widely considered one of Washington's most significant works of modern architecture. Because of the museum site's close proximity to the United States Capitol, the Smithsonian Institution wanted a building that would be architecturally impressive but would not stand out too boldly against the Capitol Building. St. Louis-based architect Gyo Obata of Hellmuth, Obata and Kassabaum accepted the challenge and designed the museum as four simple travertine-encased cubes containing the smaller and more theatrical exhibits, connected by three spacious steel-and-glass atriums which house the larger exhibits such as missiles, airplanes and spacecraft. The museum, built by Gilbane Building Company, was finished in 1976. The west glass wall of the building is used for the installation of airplanes, functioning as a giant door.