The Smithsonian Institution maintains some lovely gardens and grounds around their museums. Yesterday, Bob and I visited two of them; the Ripley Garden- a narrow garden with a pathway that winds between the Arts and Industry Building and the Hirschhorn Museum and the Enid A Haupt Garden behind the Castle Building. Walkers can easily cut through to the mall from Independence Avenue by walking along the pathway of the Ripley Garden. It is narrow but filled with mostly small scaled plants, many of which were in bloom after a very cool March. It also has benches so you can sit and rest those tired sightseer feet.
The Haupt Garden is on the Independence Avenue side of the Smithsonian Castle building. Even though it is on ground level it is really a rooftop garden since several different museum buildings are under the garden and have entrances among the plantings. The Saucer Magnolias were in bloom along with one weeping cherry (I think). The surrounding buildings and the underground warmth of this rooftop garden make this ecosystem different from the general area around DC. This makes it possible to plant varieties that otherwise might find it too cold.