Old Town Square, Prague
From Tardis Wiki, the free Doctor Who reference
There was a square in Prague. It had stone steps.
In 1999, the Ninth Doctor had a conversation about early reggae records with "Eddie Duggan", who had just come out of a club at 4AM. (PROSE: Have You Seen This Man?)
Behind the scenes
Location information
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 to the right is probably a good indicator of the DWU location of Old Town Square, Prague.