Cardiff Space-Time Rift

The Cardiff rift was a time rift in the city of Cardiff, in Wales.

History
The rift was known about at least in 1869 by the Gelth, a gaseous race which had their physical bodies destroyed during the Time War, who went through it to try and take over the bodies of dead Humans, and then eventually attempt to invade the planet and kill all Humans for their entire species. (DW: The Unquiet Dead)

The rift was later used in September 2006 by both the Tenth Doctor to refuel the TARDIS, and by the last of the Slitheen Family on Earth, Blon Fel-Fotch, disguised as Margaret Blaine, now mayor of Cardiff, to build a nuclear power station on it and initiate meltdown, blowing the Earth apart by the rift, and riding to safety on her tribophysical waveform macro-kinetic extrapolator. (DW: Boom Town)

In 2007, the Torchwood Institute set up a denomination of itself, Torchwood 3, at the rift, and led by Captain Jack Harkness. The site was chosen because:
 * 1) It was at the Cardiff rift
 * 2) Where the TARDIS landed the previous September, there was a perception filter making the people who come up the lift (and the lift itself) in the Torchwood hub invisible to outsiders. (TW: Everything Changes)