Metro access & generator is an access tunnel from Tenpenny Tower to the Metro system under the Capital Wasteland. Entry is sealed off by a sturdy containment door, but can be opened with a terminal in the generator room, which can only be accessed from a staircase behind Tenpenny Tower using a key. The first room is used as storage and contains no valuable loot for the player.
Three short passageways lead to two separated rooms with a few generators. The room accessible from the outside has a terminal which allows the player to unleash the feral ghouls on the inhabitants of Tenpenny Tower.
Opening the large containment door (which is opened by accessing the terminal on the opposite side of the wall) will result in the ghouls invading Tenpenny Tower and killing the inhabitants.
In the Tenpenny Tower quest if you haven't killed Roy Phillips and you see the ghouls you can shoot them through the screen door.
Metro access & generator appears only in Fallout 3.
With some clever use of the third person camera, the player can access the terminal from the opposite side of the glass. Normally, complicated scripted events are triggered by opening the blast door (part of the Tennpenny Tower quest). If the player accesses the terminal without the proper set-up for these events, the game might crash almost instantly after unlocking the doors.