The "Freer Gallery of Art" & the "Arthur M. Sackler Gallery" belong to the finest gems of the capital´s museum collection (asia.si.edu ). They are part of the outstanding museum row along the Independence Avenue. The museums are closely connected, visitors could view them as just one big collection.
Both museums focus on Asian arts, including arts of the Islamic world, ancient Near East, and ancient Egypt. According to Wikipedia together they form the Smithsonian Institution's national museums of Asian art (wikipedia). You also can find there a significant collection of American art.