pera is an inherently theatrical medium that does not lend itself readily to the realism of film treatment. The shining exception is Puccini's Tosca, an action-packed melodrama that unfolds in three taut and gripping acts like the meatiest of Hollywood films noir. And unlike most operas, these three acts are set in three very specific Roman locales. Thus this 1976 film takes place in the church of Sant'Andrea della Valle (Act 1), the Palazzo Farnese (Act 2), and the Castel Sant'Angelo (Act 3).

Overview from themoviedb.org