The Forbidden Zone dome, known as the X-42 robo-warfare facility before the exile of Mobius, is a location in the north-east of Big MT. It was originally named the X-42 robo-warfare facility, but was changed by Dr. Mobius after he left the Think Tank. The door to this facility is locked until the Courier has spoken to Dr. Klein as part of the quest Old World Blues.
The workshop area is comprised of a single, vast room that appears to occupy most of the inner volume of the building's dome. In the center is a large cargo elevator, on which resides the X-42 giant robo-scorpion. Around the perimeter of the room are several staircases leading to raised walkways and observation rooms; some containing terminals with information on the giant robo-scorpion. This information can be used to damage or disable the scorpion. One terminal in particular, located on the highest catwalks in the room, says that it can be used to shut down the giant robo-scorpion remotely, but actually resets the giant robo-scorpion to not be hostile towards the Courier. Methods of assisting in attacking the giant robo-scoprion include: activating turrets to fire upon it from a terminal, and starting up target drones to keep it occupied from a terminal.
The Forbidden Zone's dome is similar to The Think Tank's, but is in significantly worse condition: the lighting is sickly green, the equipment is rusted, broken, or otherwise mostly unusable, and Dr. Mobius has covered most of the surface in the main room with intricate scrawls of notes and formulas. In the six smaller rooms located off the upper tier, stored office furniture containing random loot can be found, along with what appears to be Dr. Mobius' private stash of Mentats. Located at the top of the main staircase, in a storage tank, is the Courier's brain.