Dupont Circle Station

 is part of the Metro system under the Capital Wasteland. It is mainly collapsed and you have to go through a Raider-infested cave to get to Metro Central.

Notable Loot
Lying, Congressional Style is in the room with the Protectron, on a desk in a bin, next to the door

Bugs
Just past an area with several raiders and turrets, there is a utility gate. If the player has Dogmeat as a companion, he will get stuck trying to pass through the gate and run, turning in different directions. This can be overcome by pushing him through and closing the gate behind yourself.