ACC transfers responsibility of aircraft to the tower. Tower's Departure and Arrivals Controller clears the pilot for landing. Tower stays in touch with GTAA field maintenance, especially in bad weather. The taxi route is set by the GTAA and may be dictated by construction work. GTAA handles movement of passengers into the gate areas, and checks suspicious luggage.
Pilot calls the tower to get airway clearance.
Apron Control directs the aircraft to the taxiway, and transfers it to the tower's Ground Position Control. Ground control hands off to the Departure and Arrivals Controller, who clears it for takeoff. As the landing gear comes up, the tower transfers control to the ACC's Terminal Controller, who guides the plane out of the airport. It's also the kind of bunker that James Bond villains dream of. If necessary, any of these feeds can be projected on a large screen at one end of the room.