Franklin Metro Utility

 is a few Metro utility tunnels, part of the Metro track tunnels, and a cave system. It's slightly radiated, heavy in places, and partially waterfilled.

The tunnel loops back onto itself, and you can drop down a hole in the floor to reach the beginning after you've been through. Be warned that it's quite easy to become stuck in the dumpster that the player drops into.

This is an amazing area to loot if you're into creating items at workbenches. Not only is there a workbench in the first room and at the end of the loop (before you drop down) but there is almost one of every item you'll need for your creations.

Inhabitants

 * A lot of Feral Ghouls and Glowing Ones.

Notable loot
Duck and cover located in a ticket booth on a raised platform its hidden by sheet metal walls
 * Five Stealth Boys (including the one mentioned at map point A, see below).
 * Two are directly to your left when you enter the area, in the doorless metal tool closets.
 * One is at map point A
 * Two are at the top of the map (where it loops around) on a shelf before you drop back down to the beginning.
 * Two Pre-War Books in the upstairs part of the first room, in a bit and slightly to the left of the entry/exit door and immediately to the right of the open dumpster with the empty oil drum (if you look above you, this is also where you will eventually drop through at the end of the tunnel loop).
 * Tumblers Today near the door to Falls Church/Mason Dst Metro. It's in the downstairs part of the first room to the right of the turret.  The book is on top of an average locked mine box where you fight a lot of glowing ones.
 * (A) Guns and Bullets, downstairs in the center of the second room (not the one with the turret) on a desk, along with a Stealthboy.
 * (B) A very useful Radiation Suit and a Mini Nuke at the end of the waterfilled tunnel.
 * (C) Burnmaster in a heavily radiated end of the tunnel, in a freight car (there is also a Nuka-Cola Quantum next to the Burnmaster).
 * (D) U.S. Army: 30 Handy Flamethrower Recipes in a bookshelf.