Southwark was a town in London on the south bank of the Thames.
The Globe Theatre was built in Southwark. In 1599, the only performance of Love's Labour's Won temporarily brought the Carrionites to Earth with the power of words, but William Shakespeare, aided by the Tenth Doctor and Martha Jones, devised his own words to send them back. (TV: The Shakespeare Code)
Richard Lazarus was from Southwark. During the London Blitz, he hid in the crypts of the Southwark Cathedral. (TV: The Lazarus Experiment)
In 2008, Richard Lazarus presented his rejuvenation device in Southwark. It mutated him into a monster which killed several people. he again hid in the cathedral's crypts as he had done during the Blitz. Martha Jones and the Tenth Doctor found him and he chased Martha up the bell tower. The Doctor used the cathedral's organ to distract him and he fell to his death. (TV: The Lazarus Experiment)
Behind the scenes
According to non-narrative information in the DWBIT Daleks vs Cybermen Special, in 2007, Southwark was at the forefront in the brief Battle of Canary Wharf between the Cybermen and Daleks. Many casualties and much damage occurred across the streets of Southwark. V. J. Ellison commented on the battle at a later date.