The Danger Room is a fictional training facility built for the X-Men of Marvel Comics as part of the various incarnations of the X-Mansion.
In the early books it was filled with traps, projectile firing devices, flamethrowers, and mechanical dangers such as presses, collapsing walls and the like intended to challenge the trainee. Meanwhile, an observer is in the overhanging control booth managing the room's mechanisms to oversee the exercise while manually ensuring the subject's safety. Later the Danger Room was upgraded with machines and robots for the X-Men to fight against.
After befriending the Shi'ar the X-Men rebuilt the Danger Room with Shi'ar hard-light holographic technology. These upgrades were largely added by Dr. Hank McCoy (Beast). The Danger Room is located in the X-Mansion; every destruction of the latter led to a rebuilding, and usually upgrading, of the Danger Room. The training facility has endured a lot of damage over the years, usually from X-Men training or X-Men going rogue, as Colossus did during The Muir Island Saga. Supervillains have dealt critical damage to it as well as taking over the facility, especially Arcade. The security and safety protocols that ensure the safety of anyone using the Danger Room have frequently been disrupted, tampered with by villains, failed, or have been completely negated in all the years of its use, each time happening more frequently as the room began to get more and more upgraded.
It is suggested in the X-Men Official Guide that the objects in the danger room are holograms surrounded by force fields, supposedly confirmed in Astonishing X-Men when a student managed to kill himself by jumping from a holographic cliff face. It is also revealed that the Danger Room can display holograms in only 32-bit color.
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