The Smithsonian Institution

Spanning art, history, science, and culture, the Smithsonian Institution’s holdings range from design and decorative arts to scientific specimens, natural history collections, and African American cultural artifacts, as well as photographs, archival materials, and ethnographic objects.
Smithsonian Institution Open Access is a program that offers millions of images, data, and media freely available to the public from across the Smithsonian’s twenty-one museums, libraries, and archives based in Washington, D.C. and run by the federal government. You can search for them on Curationist.