The Library of Congress is the largest library in the world by shelf space and number of books. It has a total of 147,093,357 items which includes 22,194,656 cataloged books in the Library of Congress classification system, 11,748.914 books in large type and raised characters, incunabula (books printed before 1501), monographs and serials, bound newspapers, pamphlets, technical reports, and other printed material, 13,149.787 items in the nonclassified (special) collections. [Source : http://www.loc.gov ].
The Library of Congress was established on April 24, 1800, and is the oldest federal cultural institution in the United States. The Library of Congress is physically housed in three buildings on Capitol Hill. They have a conservation center in rural Virginia. A library user need pass through security only once in a single visit because the Library's Capitol Hill buildings are all connected by underground passageways.
The Thomas Jefferson building, the main building of the Library and is the oldest of the three buildings, was first opened in 1897. Known originally as the Library of Congress Building or Main Building, The Thomas Jefferson Building took its present name June 13, 1980. The Thomas Jefferson Building is located on First Street SE between Independence Avenue and East Capitol Street . The John Adams Building is located in the block adjacent to the Jefferson Building on 2nd Street SE. It was originally build as an annex to the Jefferson Building. On January 3, 1939, it opened its doors for the first time for public.
The James Madison Memorial Building, constructed from 1971 to 1976, serves as the official memorial to President James Madison. Opened in 2007, The Packard Campus for Audio-Visual Conservation is the Library of Congress's newest building. The library also has off-site storage facilities for less commonly-requested materials.
The library is open to the general public for academic research and tourists. Only those who are issued a Reader Identification Card may enter the reading rooms and access the collection. The Reader Identification Card is available in the Madison building to persons who are at least 16 years of age upon presentation of a government issued picture identification (e.g. driver's license, state ID card or passport). However, only members of Congress, Supreme Court Justices, their staff, Library of Congress staff and certain other government officials can actually remove items from the library buildings. Members of the general public with Reader Identification Cards must use items from the library collection inside the reading rooms only; they are not allowed to remove library items from the reading rooms or the library buildings.