Boston Avenue was a street in Washington DC where, at its intersection with 8th Street, a PhiCorp warehouse containing millions of painkillers was located. To distract a police officer for long enough to render him unconscious, Gwen Cooper asked him where Boston Avenue was, and erroneously asked if it were Boston Road or Boston Street instead. (TV: Dead of Night)
Real world location
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 Boston Avenue.