The location of KAIROS headquarters might be in Olympia City however there is no information about the exact position of this place.
RooftopThe rooftop is quite a cozy area with lots of vegetation, fairy lights and benches with cushions and a little pond in the middle. Seven describes it as "warm and peaceful". There is an airstrip beside it for an aircraft to land.
Third HallwayThis hallway leads to the main lobby where the doors are locked with a particular technology.
Main LobbyThe main lobby is the central room of the base. It's where the elevators are located. The decor are similar to the one on the rooftop. It's a very open area with a high ceiling and walls made of glass windows.
In the game
KAIROS HQ remained a secret place until the attack at PHASe HQ.