Main Reading Room at the Library Of Congress in Washington DC. View to the Beaux Arts architecture style with fine decorations, murals, paintings, marble halls, columns, carved hardwoods and a stained glass dome. The Library of Congress is the research library that officially serves the United States Congress, but which is the de facto national library of the United States. It is the oldest federal cultural institution in the United States. Image is also available as a black and white print.