Centre of the Time Vortex

The exact centre of the space-time vortex was a location which was the epicentre of all reality, connecting all timelines of possibility theory. (AUDIO: He Jests at Scars...) Despite it being impossible, Maruthea was built here. (COMIC: Party Animals)

The Valeyard from a parallel universe berthed his TARDIS at the "perfect axis" of the centre of the space-time vortex in attempt to control history. He found himself overwhelmed by the possibilities, and he and Melanie Bush were trapped in his TARDIS in a possibility projection in which Chronopolis ruled time from their location. However, this projection faded after a decade, leaving the two permanently trapped in their TARDIS as the universe healed the damage they caused.

Among the timelines the Valeyard viewed from the vortex's centre included his own, one where Mel died on Heritage, one where Mel died in a spaceship crash, and one where the Doctor went on to travel with Evelyn Smythe, Ace, Hex, Charley, and C'rizz. (AUDIO: He Jests at Scars...)