The Library of Congress is a research library that officially serves the United States Congress and is the de facto national library of the United States. Founded in 1800, it is the oldest federal cultural institution in the country and one of the largest libraries in the world. The library is housed in three buildings on Capitol Hill in Washington, D.C.: the Thomas Jefferson Building (completed in 1897), the John Adams Building (1938) and the James Madison Memorial Building (1976). It also maintains the National Audio-Visual Conservation Center in Culpeper, Virginia, and a storage facility in Fort Meade, Maryland. The library's functions are overseen by the librarian of Congress, and its buildings are maintained by the architect of the Capitol. This photograph, taken by William Henry Jackson, shows the Thomas Jefferson Building around 1902.Photograph credit: William Henry Jackson; restored by Mmxx