Fallout 3 locations

General information
Without any of the available add-ons installed, there are 163 marked locations in Fallout 3 provided you have the Lawbringer perk or the Contract Killer perk; without it there are only 162 as the Regulator HQ and the Scrapyard Office are not available. It should also be noted that the Vault 101 map marker is not counted in the Pip-Boy 3000 "discovered locations" statistic, resulting in a maximum displayed value of 162 discovered locations (161 without Lawbringer or Contract Killer).

Operation: Anchorage, The Pitt, Broken Steel, Point Lookout, and Mothership Zeta add a total of 10 additional marked locations to the Capital Wasteland map and 52 more on separate world maps, coming to a grand total of 225 marked locations (223 without Lawbringer or Contract Killer). Of this total, only 221 (220 without Lawbringer or Contract Killer) are counted towards the "discovered locations" statistic in the stats section of the Pip-Boy 3000.

Capital Wasteland

 * Note: Unmarked locations are denoted in italics.

Downtown DC (Washington, DC)

 * Note: Unmarked locations are denoted in italics.

Adams Air Force Base
Adams Air Force Base can only be accessed if you have the add-on Broken Steel.
 * Adams Storage Facility
 * Air Control Tower
 * Mobile Base Crawler

The Pitt
The Pitt can only be accessed if you have the add-on The Pitt.

Point Lookout
Point Lookout can only be accessed if you have the add-on Point Lookout.

Mothership Zeta
Mothership Zeta can only be accessed if you have the add-on Mothership Zeta.