The Armacham Technology Corporation Headquarters is an office complex located in the city of Fairport, outside of the Auburn District. It is unknown if this is the true corporate headquarters, or if it is just the regional headquarters, since the ATC Board of Directors is not located at this building. However, several top employees of the company, including Harlan Wade, Charles Habegger and Marshall Disler work there. Throughout the course of F.E.A.R., the building is systematically attacked by Alma Wade and her son, Paxton Fettel, both of whom hold grudges against Armacham and its employees.
The Headquarters are assaulted by Replica forces soon after the start of the invasion of the South River Wastewater Treatment Plant. A Delta Force Recon team  is the first unit to enter, and are quickly killed by Alma Wade, who melts their flesh from their bones. The F.E.A.R. Point Man mounts a UH-60 Blackhawk Helicopter and pursues Paxton Fettel after Fettel is extracted from the water plant by a Replica Hind D Gunship to this location. Two Delta Force operatives are sent in with him, but are killed at the HLZ. The Point Man proceeds to search for Fettel, killing most of the Replicas garrisoned inside the building. While exploring the offices area, the Point Man comes across Aldus Bishop, an employee being held hostage. Douglas Holiday and another Delta Force team attempt rescue, but ATC Security Guards open fire during extraction, killing Bishop. The Point Man also meets Norton Mapes in the building.
During the attack, almost all Armacham employees employed at the Headquarters are killed, with Norton Mapes and Alice Wade being the only two people known to escape the building. The Replicas throw the employee's bodies down an elevator shaft, though some bodies are left lying around the building, including one hidden within the ceiling. Evidence of the attack is seen everywhere, with blood stains covering floors, walls, and ceilings. Amidst the chaos, Armacham sends in its own personal forces to quiet those who know of Armacham's top secret experiments, particularly those involving Alma and Fettel.
Before Alice Wade can be extracted out of the Armacham HQ via UH-60, it is shot down by a Replica Hind, forcing her to leave using her car, which eventually leads to her capture by Fettel.
For the most part, the Point Man can hear several public radio news segments regarding the ATC headquarters. It is known that neither ATC or the US government has openly discussed the situation at the headquarters (for obvious reasons), and a blockade was set to halt anyone from entering the building. Technically, this left the public in the dark.
The fate of the ATC HQ after the Origin Facility Explosion is unknown, as it was well away from the Origin Facility itself, although it is likely to have been partially destroyed, or at least damaged, by the blast.
The ATC Headquarters is briefly mentioned at the beginning of the game. In a response to Redd Jankowski's complaints, Manuel Morales mentions that several Delta Force operators were killed when infiltrating the building, and says "the situation is getting out of control."
- ATC Headquarters is the setting for both versions of the Bonus Mission.
- This is the area where Unmanned Aerial Vehicles are first introduced. ATC Security Guards are also introduced here.
- Norton Mapes is encountered most often in this section of the game.