Inside some of the most unique collections at the Library of Congress as it celebrates 224th anniversary

The nation's capital is full of towering statues and monuments honoring American presidents and legends. But inside the Library of Congress, it's possible to find more obscure and real-life mementos of those same icons. 

The Library of Congress was founded in 1800, and will celebrate its 224th anniversary this year. It's the largest library in the world and adds about 10,000 items to its collection each day. That collection plenty of unusual relics, like locks of hair. 

For centuries, long before photography was affordable, it was common practice to send or gift locks of one's hair as a sentimental keepsake, according to Librarian of Congress Carla Hayden.