Which Welsh city was Sherlock filmed in primarily?

Sherlock was filmed primarily in Cardiff, Wales. The production used the Welsh capital and its surrounding locations to stand in for modern London, while also filming selected scenes in London when the real city’s architecture was necessary.

Production was based at Hartswood Films’ Cardiff unit, established in connection with the BBC’s drama production activity in Cardiff Bay. Cardiff offered lower filming costs than London and contained locations that could convincingly double for streets, buildings and interiors in the story’s London setting.

The show’s Welsh production base is easy to overlook because Sherlock is unmistakably set in London. The programme’s fictional world includes Baker Street, Scotland Yard and other London landmarks, but many of those images were created in Cardiff. This does not mean every scene was filmed there: London location work remained important, especially for recognisable exterior shots.