Scrapyard

Scrapyard is a location south of Minefield. From Vault 101, it is northeast, past the Potomac River. More specifically, from Vault 101, in your map it is 3 squares north and 3 squares east almost exactly. It can be hard to find because it is somewhat of a depression in the ground. Looping along the south side of Scrapyard is an elevated railway, and south of that is geography sloping downwards into the river basin.

The Scrapyard can be entered through several breaches in the southwest, west, or north sides or through a gate on the south side.

In the northeast corner of scrapyard Dogmeat can be found fighting bandits. You will hear gunfire as you near this location.

This area has several radioactive pools that can be avoided, but appears to be empty of useful items. There is a locked shed in the scrapyard that requires a key to enter.

There is, however, a useful "safe" in the top Northwestern area. It contains three skill books. Look for the big red train car to the right of a radiation cesspool. Touching the red car's southern tip is a bus/train car that is cut in two. Enter the bus and look for two stairs (for leaving the bus) facing south. On the ground is John's Treasure Box. It looks like an ammunition box and is locked (hard). Inside are: The key can be found on a random Wastelander, who you'll find being attacked by dogs near Meresti Station, Arlington Library, Bethesda Ruins and possibly other locations. He will also have a note leading you to the Scrapyard and John's Treasure Box.
 * Grognak the Barbarian
 * U.S. Army: 30 Handy Flamethrower Recipes
 * Guns and Bullets

Appearances
Scrapyard appears in Fallout 3