One relatively unknown night activity is the spectacular walk from the Arlington Cemetery metro station (blue line) to the Lincoln Memorial, with all the lights reflecting in the Potomac River and Arlington House on the hill behind you. The bridge has minimal car traffic, wide sidewalks, and good lighting. There are always a lot of people at the brightly lit Lincoln Memorial every night, but I don't know exactly how they get there. I wouldn't recommend any of the other routes. The yellow line give you a close view of the Jefferson Memorial out the windows, but the nearest stop is not very close. On some trips, the only time I drive my car into the city is to visit the Jefferson Memorial at night.
