The office building is a building in Little Lamplight.
The Little Lamplight office building is located directly to the right when the Lone Wanderer enters the main gate to Little Lamplight. The building consists of a short corridor with three small rooms off to the right at even intervals. The first room is a classroom run by Joseph. The second room is the office of Lucy, Little Lamplight's doctor. The third room is where Lucy sleeps and has a sign on the wall stating "The Doctor is in!" There are usable beds in the second and third rooms.
The Little Lamplight office building appears only in Fallout 3.