Zone X

Zone X was a location on Skaro in its distant future. It was guarded by the spiked Zone X Daleks and contained a lift that went straight down to the very heart of the planet, for which reason it was out of bounds for the humanoid slaves the Daleks kept on Skaro by then.

It was on Zone X that the Doctor's TARDIS materialise when, for the first of his two Tests of Time, the Father of Time sent the First Doctor and Susan Foreman to Skaro's future, mere moments before the planet's final implosion. The Doctor and Susan were able to survive the ordeal by hiding at the heart of the planet, "riding out the storm" as the planet tore itself apart around them. This satisified the Father of Time, who deposited them back into the TARDIS and drove said Ship to land at 76 Totter's Lane, where a "new life" awaited the two. (COMIC: The Test of Time)