After Paul Denton fails his mission and is fired from UNATCO, JC Denton finds him at the 'Ton Hotel, where he is ordered to go to the HQ to gain proof of UNATCO's corruption and once convinced, to send a signal to warn Silhouette of the impending raid in Paris.
The HQ contains a computer on the roof, used for sending signal to silhouette. Level 3 contains a medical bot and a security console to open the basement, the login information can be found behind trashbags outside the HQ. Level 2 contains UNATCO troopers discussing Walton Simons and the files that Paul found on UNATCO. Level 1 contains a repair bot and a hidden entrance to the basement which is opened by the level 3 computer, a nanokey can be found in the bathrooms for the basement doors.
The basement is filled with lasers, cameras, and turrets. A datacube can be found on top of a cabinet giving login information to the roof computer, on top of a computer block is another datacube confirming Joseph Manderley's corruption. In Deus Ex: The Conspiracy, the basement is less maze-like and is reduced to a single room protected by a keypad, containing a camera, turrets and the datacubes for the roof computer.