The Third Man is a 1949 British film noir, directed by Carol Reed and starring Joseph Cotten, Alida Valli, Orson Welles, and Trevor Howard. Critics rank it as a masterpiece, particularly remembered for its atmospheric cinematography, performances and unique musical score.The screenplay was written by Graham Greene, who subsequently published the novella of the same name (which he had originally written as preparation for the screenplay). Anton Karas wrote and performed the score, which used only the zither; its iconic title theme topped the music charts in 1950. Six weeks of principal photography was shot on location in Vienna. Production moved to the Worton Hall Studios in Isleworth and Shepperton Studios near London. The scenes of Harry Lime in the sewer were shot on location or on sets built at Shepperton, with most of the location shots using doubles for Welles. Reed, however, claimed that despite initial reluctance, Welles quickly became enthusiastic and stayed in Vienna to finish the film.

The Third Man (1960)   http://www.imdb.com/title/tt0041959/