Shada
From Tardis Wiki, the free Doctor Who reference
This article is about "Shada" as used in the Doctor Who Universe. For other uses see Shada (disambiguation)
Shada was a planetoid (or asteroid) into which Time Lords built a prison for would-be conquerors of the universe, including the Master. (Prisoners of the Sun)
The location of Shada became lost to all but Salyavin, a Time Lord disguised as a Professor Chronotis at the University of Cambridge, Professor Chronotis. (DW: Shada)