I'm in the Capitol Building and worked my way to the east wing and to the double doors to the Presidential metro. But it requires a key or, according to the vault boy symbol, the power to be turned on. I backtracked through the entire building -- pretty thoroughly, I thought -- but could find neither. Could some kind person offer me a hint? Many thanks.

I don't think there is a key. Have you finished Broken Steel?

No, I'm working my way through it now. This is part of it.

You have to go through the tunnels at White House Plaza to get to the Presidential Metro. The Capitol Building door doesn't open until after you've finished the Broken Steel quests.

Okay. Thanks a lot.