Taking the Yellow line from L’Efant Plaza to Pentagon gives you one of the best views of the capital from the metro. Just keep watching on the right side because it passes fairly quickly. On the way back you may also catch a glimpse of an airplane taking off from the National Airport. Besides the great architecture of underground stations, most stations also feature works of art. Perhaps the best is right outside the Silver Spring station, where a mural of penguins as metro riders adorns the subway underpass.