The Library of Congress which is located right next to the US Capitol is a beautiful sight. I have passed the Library of Congress tons of times without realizing you could go inside.
The Library of Congress is the largest library in the United States containing more than 38 million books. With parts of the collection spanning over 430 languages.
Library of Congress on Google Maps
Main Reading Room at the Library of Congress
Twice a year the Library of Congress opens the main reading room up to the public to explore. This gives you the ability to explore the main reading room and even enter record keeping rooms. The reading room is typically open to the public on Memorial Day and Presidents’ Day.