RevBladeZ
First time out of the vault

Lost Hills is the headquarters of the entire Brotherhood of Steel but the thing is, NCR and the Brotherhood have been in war for quite a while now and the location of Lost Hills was public knowledge even before there was an NCR. Hell, Lost Hills is located in Maxson, one of the five founding states of NCR.
So with the war between NCR and Brotherhood, combined with the fact that NCR has definitely been pushing the Brotherhood back, it really makes you wonder what has happened to the publicly known headquarters of the Brotherhood.
Since it is their headquarters, the Brotherhood definitely would have its heaviest defences around there but at least in Fallout 1, Brotherhood got their food entirely through caravan trade and places like Hub are now NCR states so NCR could prevent caravans from going to Lost Hills. There's also the thing that Lost Hills is an underground bunker so NCR wouldn't necessarily even need to get inside, just destroy the entrance and trap the Brotherhood there. Though it is also likely that the Brotherhood would have much better defenses around the entrance than it did in Fallout 1 and it wouldn't be unreasonable to assume that Lost Hills would have an emergency exit in case the main entrance was destroyed. Brotherhood having farmland around Lost Hills now wouldn't be unreasonable either.
So with the war between NCR and Brotherhood, combined with the fact that NCR has definitely been pushing the Brotherhood back, it really makes you wonder what has happened to the publicly known headquarters of the Brotherhood.
Since it is their headquarters, the Brotherhood definitely would have its heaviest defences around there but at least in Fallout 1, Brotherhood got their food entirely through caravan trade and places like Hub are now NCR states so NCR could prevent caravans from going to Lost Hills. There's also the thing that Lost Hills is an underground bunker so NCR wouldn't necessarily even need to get inside, just destroy the entrance and trap the Brotherhood there. Though it is also likely that the Brotherhood would have much better defenses around the entrance than it did in Fallout 1 and it wouldn't be unreasonable to assume that Lost Hills would have an emergency exit in case the main entrance was destroyed. Brotherhood having farmland around Lost Hills now wouldn't be unreasonable either.