Hitler: A Film from Germany (1977)
Hitler: A Film from Germany, called Our Hitler in the US, is a 1977 Franco-British-German experimental film directed by Hans-Jürgen Syberberg, produced by Bernd Eichinger, and co-produced by the BBC. It starred Heinz Schubert, who played both Adolf Hitler and Heinrich Himmler. Along with Syberberg's characteristic and unusual motifs and style, the film is also notable for its 442-minute running time.
More at Wikipedia.