- You may be looking for Floor 0000 on a Mondasian colony ship.
Floor 000 was the lowest level of Satellite Five. All the humans, who refused to believe the existence of the Daleks, hid there while Ninth Doctor worked and Jack Harkness and others fought above. Instead of proceeding up after initial entrance, as predicted, the Daleks instead went down directly to Floor Zero and exterminated all the humans. (TV: The Parting of the Ways)