The National Arboretum often ranks lower on the list of must-see places behind the Smithsonian museums. when visiting DC. But on sunny days it's an incredible (and free) place to explore.
Established in 1927 by an Act of Congress, the Arboretum houses over 400 acres of and 9.5 miles of roadways. It's a great place for hikes or a run. The Arboretum also has an expansive Herbarium, a bonsai garden, and The National Capitol Columns.
The Arboretum's mission: To serve the public need for scientific research, education, and gardens that conserve and showcase plants to enhance the environment.