Taft Tunnel

The taft tunnel is an escape tunnel from Jefferson Memorial. The exit point is a sewer grate outside the Citadel entrance, just south of the west point of Arlington Memorial bridge. These tunnels were most likely used as a secret escape route for pre-War political figures occupying the Pentagon, but Chinese weaponry and items, including rifles, pistols and clothing, alongside a ham radio and other bits of technology, lend credence to it being occupied by Chinese spies.

Layout
The initial tunnel leads to an open room with many feral ghouls and some radioactive barrels. From there, you go down another tunnels which opens to a room with two doors. The one on the left has a very hard terminal that Dr. Li must hack to open the door in front. The door on the left is populated by Enclave soldiers. Once the front door is opened, there is another tunnel with door ways on the left that have nothing of value and a door on the right that you go through. Then there's another tunnel that leads down. From there, there's another door on the right that leads to a Brotherhood of Steel paladin using a flamer against feral ghouls. From there, you head to the right and up the ladder to the entrance of the Citadel.

Inhabitants
In the lower levels, you will encounter a number of feral ghouls, while the floors above have many Enclave soldiers, and it was once occupied by Chinese spies.

Notable loot

 * Chinese Army: Special Ops Training Manual on the desk in the room when you first engage the Enclave soldiers
 * Sugar Bombs on the same desk as the Chinese Army: Special Ops Training Manual
 * Eyebot helmet on a desk just after the second room you are ambushed by Enclave soldiers
 * Rare tortiseshell glasses [sic] are found after encountering feral ghouls for the second time in a medical room next to a skeleton holding jet on the floor as soon as you enter
 * Nuka-Cola Quantum in the second section of Taft Tunnel. Found after the second Enclave encounter and the eyebot helmet, next to a portable generator sitting on top of a wooden picnic table.
 * Nikola Tesla and You behind the generator immediately next to the Nuka-Cola Quantum

Appearances
The Taft Tunnel only appears in Fallout 3.

Behind the scenes
The name of the Taft Tunnel is named after President William Howard Taft

Bugs

 * If Garza dies from one of the Enclave ambushes, Dr. Li will tell you that she cannot leave Garza behind. If you failed the option for Dr. Li to leave him behind then you will have to restart your game to an earlier save point.
 * Sometimes when re-entering and exiting the taft tunnels after the Waters of Life quest, Dr. Li and her team of scientists may appear outside of the Citadel and next to the tunnel entrance.
 * When going through the door in the inaccessible area, Dr. Li, Daniel Agincourt and Alex Dargon may all appear in the second area of Taft Tunnels and act as if they were in the Citadel.
 * When approaching the sewer grate for the first time, you may be attacked by a super mutant. If you kill the super mutant with an energy weapon and it becomes an ash pile on top of the sewer grate, you will not be able to enter the taft tunnels. Your game will be corrupted and will have to reload from an earlier save point.
 * If you successfully convince Dr. Li to abandon Garza and proceed to the next section, the remaining members of the science team can turn into Sergeant RL3 (who was waiting in my Megaton house) and the mission proceeds normally.
 * Dogmeat (or other followers) may spawn inside the tunnels in a number of circumstances, regardless of earlier being told to wait, or return to Vault 101. (This has happened a few times on Xbox 360 but mainly appears on ps3 and pc)
 * Should you happen to complete your journey through taft tunnel with all of the four followers from the quest The Waters of Life, without any of them turning into Dogmeat (or other standard followers), you might, after leaving the tunnel at the Citadel exit, get the message that Dogmeat is waiting for you in front of Vault 101, although you never told him to do so.
 * Carrying out a sneak attack on an enemy, can result in someone from the team thinking you're being reckless and temporarily flee. While this has no specific negative effect, Dr. Li will remain crouching regardless of what stance you are in, but can be fixed by asking her to follow you again.
 * If the player hacks the terminal before Dr. Li, or simply does not allow Dr. Li to hack the terminal, you may get a bug just outside the "catwalk room" where you fight off the Enclave while Dr. Li opens the door. After the threat is cleared and the door opened Alex and Daniel continue to wait endlessly on either side of the doorway. Dr. Li and Garza still follow the player normally. Alex and Daniel remain in the same place even if the player goes to a different area and returns.