Library of Congress
The Library of Congress is the research library of the United States Congress, and the oldest federal cultural institution in the United States. Located in three buildings in Washington, D.C., it is the largest library in the world by shelf space and holds the largest number of books. The Library of Congress was established by Congress in 1800, and was housed in the United States Capitol for most of the 19th century. The Library's primary mission is researching inquiries made by members of Congress through the Congressional Research Service; although it is open to the public, only legislators, Supreme Court justices and other high-ranking government officials may check out books.