The X-Men exist in the Marvel Universe with other characters portrayed in Marvel Comics series. As such, it is unsurprising that they often meet characters from other series, and the global nature of the mutant concept means the scale of stories can be highly varied. The X-Men fight everything ranging from mutant thieves to galactic threats. Historically, the X-Men have been based in the Xavier Institute, near Salem Center, in north-east Westchester County, NY, and are often depicted as a family. The X-Mansion is often depicted with three floors and two underground levels. To the outside world, it had acted as a higher learning institute until the 2000s, when Xavier was publicly exposed as a mutant at which point it became a full mutant boarding school. Xavier funds a corporation aimed at reaching mutants worldwide, though it ceased to exist following the "Decimation."