Chameleon Circuit

A Chameleon Circuit is a fictional device from the television sci-fi series "Doctor Who." It is used by the Time Lords as a form of camouflage for their time travel machines, TARDISes. The Chameleon Circuit blends the TARDIS into its surroundings by making it appear to be something that people of the place and time where it has landed would expect to see everyday. The Doctor's TARDIS is permanently stuck in the form of a British 1950s Police Telephone Box. While there is the suggestion that the ship took on this form in the first episode - set in 1963 - the Ninth Doctor explains that it landed in 1950's England, then broke, and The Doctor claims he could, but doesn't fix it because he "rather likes it" (-Episode Boom Town, 2005 series). Despite the fixed form it continues to go mostly unnoticed in present-day episodes due to apparent human ignorance; "If you whack a great big blue box in the middle of a street, what do people do? Walk right past it." (-Episode Boom Town, 2005 series)