One of my favorite places in Washington, DC is the National Gallery of Art. I particularly love the East Building. Beyond the amazing art, the architecture of the building itself is stunning.
The building recently reopened after a three-year renovation including creating additional gallery space and a lovely rooftop terrace with sculptures including the now famous "Hahn/Cock" by Katharina Fritsch on long-term loan from Glenstone. When I last visiting, the three towers each houses the following artists' works: Barbara Kruger, Alexander Calder, Mark Rothko, and Barnett Newman. Some of these exhibits will be limited time while others will rotate the works displayed or remain longer term.
I really enjoyed checking out the new digs during NGA Evenings at the Edge program where the museum stays open late with performances, music, and pop-up talks. (NOTE: One such night remains in April, so be sure to sign up if you haven't been yet...or if you have and want more!)