"The Third Man" (1949) Orson Welles and Joseph Cotton in "The Cuckoo Clock" Scene

The classic film that was voted number one of the Top 100 films by the British Film Institute, "The Third Man" was based on a screenplay and novella by Graham Greene. (The latter was published a year after the film was released.) It was directed by Sir Carol Reed and produced by Alexander Korda.

The story is about a down-and-out American writer of pulp Westerns (Joseph Cotton as Holly Martins) who comes to the four-power occupied city of late 1940's Vienna to take his old friend Harry Lime up on a job offer. It turns out that Lime has faked his demise in order to throw the British police off on his doings as a black-marketeer of, among other things, secretly diluted (and lethal) penicillin to children's hospitals.
Lime is both a callous murderer and a genuine "bon vi-ant", and Orson Welles plays both aspects of the character to perfection. (Ironically, despite all his work on film as a director/actor, this relatively minor role was the one he was most famous for during his heyday.)

The final part of the scene with Lime's recounting the Italian City-States and Swiss cuckoo clocks was Welles' inspiration.

When Martins finds out Lime is still alive, he tracks him down to the Russian Sector of the divided city to find out what has happened to his friend. Here the Machievellian philosophy of the fugitive Lime is brought out in crystal clarity above the city on a dizzying and potentially dangerous ferris wheel ride. The clip here is one of the best in a series of great scenes in this movie, a true must-see film.