[Librarian of Congress Herbert Putnam, reading at his desk in the Library of Congress]

The Library of Congress Building or the Jefferson Building is the oldest of the four United States Library of Congress buildings, built between 1890 and 1897 in Washington, DC. It is located on First Street SE, between Independence Avenue and East Capitol Street. The new building was needed because of the Copyright Law of 1870, which required all copyright applicants to send to the Library two copies of their work. This resulted in a flood of books, pamphlets, maps, music, prints, and photographs. After Congress approved construction of the building in 1886, it took eleven years to complete. The building's main architect was Paul J. Pelz, born in Prussian Silesia, initially in partnership with John L. Smithmeyer, a native of Vienna, Austria, and succeeded by Edward Pearce Casey during the last few years of construction. More than fifty American painters and sculptors produced commissioned works of art. The building opened to the public on November 1, 1897, met with wide approval and was immediately seen as a national monument. The building name was changed on June 13, 1980 to honor former U.S. President Thomas Jefferson.

The lantern slides first produced for the 17th century's “magic lantern” devices. The magic lantern, also known by its Latin name Lanterna Magica, an image projector that used pictures on transparent plates (usually made of glass), one or more lenses, and a light source, used for entertainment. The earliest slides for magic lanterns consisted of hand-painted images on glass, made to amuse their audiences. After the invention of photography, lantern slides began to be produced photographically as black-and-white positive images, created with the wet collodion or a dry gelatine process. Photographic slides were made from a base piece of glass, with the emulsion (photo) on it, then a matte over that, and then a top piece of a cover glass. Sometimes, colors have been added by hand, tinting the images. Lantern slides created a new way to view photography: the projection of the magic lantern allowed for a large audience. Photographic lantern slides reached the peak of their popularity during the first third of the 20th century impacting the development of animation as well as visual-based education.