The first modern-art museum in the country (opened in 1921) houses a small but exquisite collection of European and American works. Renoir’s Luncheon of the Boating Party is a highlight, along with pieces by Gauguin, Van Gogh, Matisse, Picasso and many other greats. The intimate rooms, set in a restored mansion, put you unusually close to the artworks. The permanent collection is free on weekdays. Download the free app or dial 202-595-1839 for audio tours through the works.
The Rothko Room, which has four of the abstract expressionist’s pieces, is worth a peek. Be aware that famous works sometimes rotate into the museum's ticketed exhibitions (in which case admission fees apply). The Phillips' Sunday chamber-music series has been making sweet sounds since 1941; concerts start at 4pm October through May, and tickets cost $40.