Wheaton .
The
whole site is quite interesting and sort of relevant to the thread.
I can't remember which scary escalator I was on last time I was DC (2000?), but it may have been Wheaton. I do seem to remember it was working on the way up, then when we came back to it, it was out of service. So we climbed down the thing. My mother with her bum knee, me with my fear of tumbling for long distances.