After leaving the James Madison Building of the Library of Congress, I tried to tour the National Archives. However, I discovered that you must have a timed tour and there were 50 people already waiting in line. So I walked across the Mall to the Hirshorn Museum and Sculpture Garden.
The museum and garden was established by an act of Congress in 1966 as part of the Smithsonian Institution. The sculpture garden features works by Alexander Calder, Auguste Rodin, and Jeff Koons. Most of the funding was federal although Joseph H. Hirshorn, who made his millions in the uranium mining industry, made a generous contribution.
Yoko Ono's Wish Tree For Washington, DC, has been a permanent installation in the garden since 2007, and has become very popular with contributions from all over the world (including mine).