“The Library of Congress is the nation’s oldest federal cultural institution and serves as the research arm of Congress. It is also the largest library in the world, with millions of books, recordings, photographs, maps and manuscripts in its collections.”

Edit:”Statistics

The Library of Congress is the largest library in the world, with more than 134 million items on approximately 530 miles of bookshelves. The collections include more than 32 million books and other printed materials, 2.8 million recordings, 12.5 million photographs, 5.3 million maps, 5.5 million music items and 59.5 million manuscripts.”

http://www.hno.harvard.edu/guide/to_do/to_do6.html