Fallout: 10 Most Evil Companies 

Big MT can be visited in the Fallout New Vegas add-on Old World Blues and, before the war, was a secret, underground, privately-contracted research facility that developed weapons and advanced technology for the U.S. military.

Originally it was located under a giant mountain but, due to a failed experiment, the entire top of the mountain was vaporized out of existence, leaving only a crater with the research base at its centre.

That should give you some idea of the sort of experiments that went on here.

The list of technologies developed by Big MT is truly insane: cyberhounds, robo-scorpions, nightstalkers, sonic emitters, stealth suits, total pacification collars, proton axes, and much, much more!

Everyone remembers the terrors of trying to escape a hoard of deadly cazadors in the Mojave desert, being poisoned to death and attacked from all angles, but not many know that these abominations were actually created at the Big MT facility and later escaped.

Not to mention that before the war, Big MT constantly performed experiments on kidnapped U.S. citizens without the public's knowledge.