You could, I suppose, include train tunnels--Keaton's OUR HOSPITALITY; THE LADY VANISHES (where the tunnel creates a clue); and of course MISSION IMPOSSIBLE's ending in the Chunnel (or for that matter, SPEED's climax in the unfinished LA subway) are all examples. I don't recall if anyone has mentioned the film version(s) of Jules Verne's JOURNEY TO THE CENTER OF THE EARTH. Speaking of Verne, Melies has his astronauts enter a sublunar tunnel in A TRIP TO THE MOON. Don Larsson, Mankato State U (MN) ---- Online resources for film/TV studies may be found at ScreenSite http://www.sa.ua.edu/screensite