There's a jungle inside Vietnam's mammoth cavern. A skyscraper could fit too. And the end is out of sight.
The same Kansas salt mines that protected over 3,300 hours of The Tonight Show With Johnny Carson from the ravages of time and Injuns has now given us another worthy pop-culture artifact: 17 "lost" minutes from Stanley Kubrick's 2001: A Space Odyssey that have been unearthed by Warner Bros. Douglas Trumbull, the film's special photographic effects supervisor, made the revelation while discussing Beyond The Infinite: The Making Of A Masterpiece, a behind-the-scenes documentary he'd been working on with David Larson.
See also, Modern Times, by BC2010.
In Vietnam, World's Largest Cave Passage