A Giant bunker shaped like a pyramid. Exploring it is related to one of the main quests of the Brotherhood of Steel. Inside you can find more than a dozen of ghouls.
In order to deactivate the alarm and unlock all doors, you must walk downstairs to the bottom and use the terminal.
In one of the laboratory rooms at the start you will find Astoundingly Awesome Tales magazine.
The door to the bomb warehouse at the end of the tunnel going down the complex can be opened using a terminal. In the room you will find a miniature atomic bomb, but you must watch out for high radiation.