Underworld

Underworld is an area where many ostracized non-feral ghouls of Washington, DC live. It is located inside the Museum of History, and exists as a small city, complete with a bar, inn, clinic, and a "hair stylist".

Most humans are tolerated, as long as they do not cause trouble. The Brotherhood of Steel are not welcome, however, as they tend to shoot ghouls on sight.

Background
The museum was featuring an exhibit on the concepts of Hell and the afterlife during the time of the Great War, as most of the remaining exhibits (including the name of that section of the Museum as well) are all themed as such.

Doctor Barrows is the mayor of Underworld, although, because of the small nature of the town, his civic duties take a backseat.

Layout
Underworld is reached through the double doors under the big skull in the Museum of American History. Griffon will set up his Aqua Cura sham outside if Take it Back! has been completed, but only on the Broken Steel add-on.

When you first enter, you'll be standing in front of the main hallway. Underworld Outfitters is in a room on the left side of the hallway, while Winthrop's office is opposite and a little farther from the entrance. The doors in the back lead to The Chop Shop.

Heading up either set of stairs will take you to the overlook. The Ninth Circle is on the left side, from the main entrance, Carol's Place on the right. In the large room at the end of the overlook, Moira Brown will be there both selling and asking you to continue with research for her survival guide (if you destroyed Megaton), and Snowflake will be hounding you for a haircut.

Inhabitants

 * ¹ Unconscious as long as Reilly's Ranger quest isn't completed
 * ² If she survives Stealing Independence and is spoken to after completion
 * ³ If you destroy Megaton
 * † Can be found wandering around in front of the entrance to the Underworld in the room with the Woolly Mammoth. He must be freed from his prison cell during Find the Garden of Eden quest.

Appearances
Underworld only appears in Fallout 3.

Behind the scenes

 * The large ruined painting on the second floor of the Concourse is "Dante and Virgil in Hell" by William-Adolphe Bouguereau.
 * Also relating to Dante and Virgil, the bar "Ninth Circle" is phrased after the travels of Dante and Virgil through the nine circles of hell.