The Time Fracture was a time anomaly and transdimensional portal which was located and observed at a former UNIT Black Site, located at coordinates 51°30'47.7"N 0°08'51.9"W, (WC: 14681 UNIT Field Log) from 8 June 1980. (WC: 14682 UNIT Field Log)
The Fracture was created (PROSE: What the TARDIS thought of "Time Lord Victorious") in 2059 when the Tenth Doctor declared himself Time Lord Victorious and changed history by saving Adelaide Brooke on Mars and returning her home to Davies Street. (TV: The Waters of Mars) The Doctor's TARDIS watched as "a paradox was born" upon her stepping onto the street, widening into the Fracture. As the TARDIS had anticipated, (PROSE: What the TARDIS thought of "Time Lord Victorious") the Doctor used the Fracture to access the Dark Times after Adelaide's suicide, arriving on the planet Andalia. (PROSE: The Knight, The Fool and The Dead)
The Fracture spread out through time, (PROSE: What the TARDIS thought of "Time Lord Victorious") such as Central London, (WC: 14683 UNIT Field Log) where UNIT began observing one of the transdimensional portals on 8 June 1980. (WC: 14682 UNIT Field Log)
Behind the scenes
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map at right is probably a good indicator of the DWU location of Time Fracture.