You can explore (US) historical pictures, maps, and more in the digital collections from the Library of Congress. The option to download of images is available. Any citation must be created by the user.
"The LOC concentrates on its most rare collections and those unavailable anywhere else. The services are a gateway to a growing treasury of digitized photographs, manuscripts, maps, sound recordings, motion pictures, and books, as well as "born digital" materials such as Web sites. In addition, the Library maintains and promotes the use of digital library standards and provides online research and reference service"