I now understand why they closed down the airport after the 2001 attacks. (Click on the link to MT's post, above.) Directly to the south of the White House is the Washington Monument. Straight across the river from that (to the southwest) is the Pentagon. The airport is directly across the highway from there. With it being that close, I'm surprised the airport open now.
Oh, and you can count me amongst those people that are concerned that data of this quality is openly available. Yes, I've enjoyed wasting more than a few minutes looking at places I've been but I'm nervous about certain people looking at places they're interested in visiting.