For those who don't know the history of the mobile lounges at Dulles, it's an interesting story (well, at least it is to me!). They were an integral part of Eero Saarinen's innovative design for Dulles, which he believed would save passengers from the long walks built into so many airports. Unfortunately, the design proved impractical, especially with the arrival of jumbo jets.

Here's a more detailed explanation:

http://www.atlasobscura.com/articles...-mobile-lounge