Big MT

The Big Empty is a high-tech military research facility in the Mojave Wasteland. Many of the Mojave's mutated creatures originate from there.

Background
A pre-war military operation, the Big Mountain Research and Development Center has remained secure ever since the Great War, its scientific secrets and treasures undisturbed, protected by robotic guardians and well-concealed by its sheer size

Nowadays, the installation, described by Elijah as a "treasure box" and "a scientific graveyard of Old World misery", houses several pre-war scientists, their personalities preserved by Think Tanks. There, they perform experiments that can only be described as atrocities on anyone unlucky enough to find themselves at the facility. People subjected to them are often damaged beyond recognition by the procedures - some could only hear static, others became gibbering wrecks. Other technologies found at the Big Empty include Holorifles, Saturnite alloy, hibernation chambers, Securitrons and the hazmat suits worn by the Ghost People. The Big Empty is also known to contain holograms, however only N.E. were able to perfect the technology, selling it exclusively to Frederick Sinclair, so the holograms of the Big Empty are far less lethal than those of the Sierra Madre.

Christine Royce, a Brotherhood of Steel Knight, came across the Big Empty in her hunt for a deserter who had abandoned his leadership post after Operation: Sunburst, fleeing into the wastes to find technology capable of wiping out the NCR. When she finally found him, he trapped her in one of the aforementioned medical research labs, modifying her brain with cybernetic enhancements to the point where she can only think and dream in numbers. The deserter fled to the Sierra Madre, taking with him a supply of explosive collars and a holorifle. Not long after, Christine was freed by a mysterious courier known as Ulysses, who encouraged her to continue her hunt.

In 2281, the Courier arrives at the Big Empty, where his/her brain is stolen by the scientists therein.

Appearances
The Big Empty was originally supposed to appear in Black Isle's canceled Fallout 3, but in later development was merged with the Leavenworth prison into the Tibbets Prison facility. Tibbets would occasionally still be referred to as the Big Empty by developers in design documents.

The Big Empty is mentioned in the Fallout: New Vegas add-ons Dead Money and Honest Hearts, and will appear in Old World Blues.