The TARDIS is the time machine utilized by the Doctor in the BBC cult television series Dr. Who. TARDIS is an acronym for "Time and Relative Dimensions in Space." The Doctor's rather unreliable type 40 TARDIS appears as a blue 1950s-style police box – but only because the chameleon circuit that allows the TARDIS to appear in any form got jammed on Earth in 1963. The internal size of the TARDIS bears no resemblance to its external dimensions. In fact, the TARDIS contains libraries, gardens, swimming pools, and even a cricket pavilion, plus two control rooms, a boot cupboard, a very large costume wardrobe and a pink Zero Room.