The ruins consist of the main street, several alleys and destroyed houses. There are upwards of twelve well armed raiders in the vicinity, on the street and in the tunnels beneath. North of the main road running through the center of the town east to west, is the entrance to the Fairfax Metro Station. There are also a pair manholes and a pit trap leading to the utility tunnels. There are also various traps that may attract the raiders' attention if set off. You may also run in to frag mines by fast-traveling here. Outside one of the houses on the outskirts of town, is a gas valve that, when repaired, allows you to burn enemies by shooting them inside the house.
The main entrance to the utility tunnels is a grating in the floor that collapses into a small rectangular hole in the center of Fairfax Ruins. A far less defended entrance to the tunnels is a manhole located to the northwest of the ruins to the east of the Brotherhood Outcast base. Inside are several raiders, ammunition boxes, aid items, and other loot.
There is also a separate subway tunnel in the center of Fairfax Ruins guarded by two raiders. This subway has no links to any other areas, but there are various ammunition boxes lying around. When entering the tunnel, there are some mines as well as a shotgun trap close to the entrance. The tunnel is, like the rest of Fairfax Ruins, inhabited only by raiders.
The place is fully inhabited by raiders, whose numbers provide them the confidence to engage in probing assaults on nearby fortified positions including the Brotherhood Outcast's HQ. A small scouting party can even be found just off the road north of town waiting to ambush unwary travels approaching from that route. Their resources are such that they even have a defense turret overlooking the northern approach into Fairfax. The group as a whole is quite well armed, with a wide variety of weapons from missile launchers, combat shotguns, and assault rifles, to even flamers, and 10mm submachine guns.
To the north of the ruins, the Enclave have set up an outpost with a deathclaw cage which will appear after the player has done the quest "The Waters of Life". Upon approaching the camp, there will usually be three soldiers and two officers present, but their numbers can change depending on the player's level. The soldiers are sometimes armed with flamers and will be busy executing several wastelanders enclosed in a cage, which may explain the bodies. This observation also suggests that a deathclaw cage was being used as a makeshift execution chamber. An Enclave Hellfire trooper may be included in their ranks if Broken Steel is installed.
It is possible to escape the pit trap with the falling grate that prevents fast travel by jumping onto the wall drain and then quickly jumping out.
A friendly Enclave soldier wearing Tesla armor and armed with a missile launcher may be encountered in the open square on the south side of the ruins (where the broken highway comes into the town). He will clear out the raiders in the area, including the raider with a missile launcher. He reports "Area secure" and the only dialogue option is "See you later".
Fairfax Ruins are the ruins of real-world Fairfax, VA. However, the ruins in Fallout 3 are comparatively smaller than the true town and the location is much closer to downtown Washington DC than depicted in the game.