Shada was the prison planet of the Great Houses.
From Shada, all of history could be witnessed. If history were ever altered so the Great Houses never existed, a backup of the Spiral Politic was stored on it to be remapped onto the universe. (AUDIO: A Labyrinth of Histories)
The prisoners of Shada were stored each in their own separate cryogenic cell, alive, but frozen in time, in perpetual imprisonment. (PROSE: Shada) They had dragon tattoos which snapped upon their release. (PROSE: Christmas on a Rational Planet)
Skagra managed a successful jail break of Shada's prisoners while in search of Salyavin, the notorious Time Lord criminal who had developed a means of projecting his own thoughts into anyone's mind. Skagra believed that with this power, he could impose his own thoughts and will on the universe. Salyavin, though, had already escaped and was living a peaceful life as Professor Chronotis of the University of Cambridge. (PROSE: Shada, AUDIO: Shada)
Grandfather Paradox was imprisoned on Shada. (Legend had it that he had been imprisoned rather than executed because "everyone was more afraid of him dead than alive.") Early during Romana's Presidency, she suffered an epileptic fit under the influence of the Carnival Queen and signed an executive order freeing three hundred prisoners from Shada, including the Grandfather, who led the freed prisoners. (PROSE: Christmas on a Rational Planet)
Faction Paradox members Justine and Shuncucker were also imprisoned on the prison planet. (AUDIO Movers) Demetra Kein infiltrated the prison planet and set all the prisoners free. Before the House Military arrived to keep order, Cousin Justine escaped in a timeship. (AUDIO: A Labyrinth of Histories)