Fallout 3: Where are the Brotherhood Outcasts based?

I know they have a main base... somewhere, but where? Alot of people tell me Fort Independence, but I've been there. I went there to get the T15b Power Armour. Am I missing something? I need to speak to there leader, so I need to find where they actually live. The Outcast's equivilant to the Brotherhood's Citadel if you will