People mover tunnel in the East Wing of the National Gallery of Art. I'd never heard about it before coming to D.C. the first time, but the National Gallery is definitely on my list of must-see D.C. places. In addition to the great art (I have some pics of the Calder mobiles coming), the building's design is interesting, as well. No, it's not like the most incredible piece of architecture you'll ever see, but little details like this (and the central rotunda and the fountain running into a glass wall near this tunnel and the cafeteria) make it worth your while. Oh yeah, and the art; I recommend the works by Monet, but I'm an art know-nothing. My sister's favorite is Argenteuil (The Promenade at Argenteuil). For some reason, on this most recent visit, I was most interested in The Houses of Parliament, Sunset and Waterloo Bridge, Gray Day.