The area found above ground is in a two story configuration; here one can find broken terminals amidst the rubble. The first sub-level has multiple holes to the basement; one is booby-trapped by a pair of laser tripwires. The lowest floor can be accessed in one of two ways: either by falling through the hole in the floor in the eastern room or by jumping down the elevator shaft and using the hatch on the elevator cart. The basement contains feral ghouls.
From the basement, one can take the elevator to the top floor. The ceiling on the top floor has mostly collapsed, affording access to the roof. There is an Advanced safe with some ammunition and some random loot inside. As the elevator will only return to the basement, the only way to leave the building is by jumping from the roof.
The second floor is accessible by walking up the hill around the building and entering through the hole underneath the "Atlantic Offices" sign. The elevator shaft is accessible here, and there are several holes in the floor that lead to the main level. There is a room with a locked security door here that is controlled from a nearby terminal.
There is a fusion core on the rooftop.
The Atlantic Offices appear only in Fallout 4.