[Men putting in place the keystone of the S.W. clerestory arch of the rotunda of 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.