Taft Tunnel

This 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.

Inhabitants
In the lower levels, you will encounter a number of Feral Ghouls, while the floors above have many Enclave Soldiers.

Notable loot

 * Chinese Army: Special Ops Training Manual on the desk in the room when you first engage the Enclave Soldiers.
 * Eyebot Helmet in the second room you are ambushed by Enclave Soldiers
 * Nuka-Cola Quantum in the second section of Taft Tunnel. Found after Dr. Li stops you for Garza, 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.

Bugs

 * Sometimes when re-entering and exiting the Taft Tunnels after the 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. (Xbox 360)
 * 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. (PS3 and Xbox 360)
 * 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. (PC)
 * 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.
 * 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. (PS3, PC)