1. 2001: A Space Odyssey
Stanley Kubrick's sci-fi masterpiece 2001: A Space Odyssey has no rival in terms of ambition; this is a film that invented so much, and has been a lasting influence on science-fiction ever since. It is a film that challenges not just technically, but thematically, also; for all of its immaculate set design and entrancing, often dreamlike imagery, the film is also philosophically provocative, riffing on the nature of technology, human existence and evolution, as well as the role of extraterrestrials. Steadily growing in reputation since its release, 2001 is now regarded by many as one of the greatest films ever made, a meditative, philosophical masterpiece that demands a lot from viewers, but will give them plenty in return. In attempting to project humanity's potential as well as theorise on the unknown aspects of the universe, this is ambition at its most artistically unrestrained. Which film do you think is the most ambitious of all time? Let us know in the comments below.