Silent Cartographer
From Halopedia, the Halo wiki
Summary
The Silent Cartographer, as referred to by the Covenant, is Halo's map room. It can pinpoint and access every room or location on or beneath Halo surface. Little else is known about this map technology.
The Silent Cartographer is protected by an elaborate security system. This system can only be activated and deactivated by manual physical contact. In order to access the Silent Cartographer one must enter a first building to disable the security system, and then enter a separate structure which contains the map room. This gives the map room double protection making access difficult and defense much easier.
