The hardest novels to film

Many people thought "The Lord of the Rings" would never be made into a film - there were simply too many characters and intricate stories in it, and it would be impossible to re-create Middle Earth. Well, director Peter Jackson proved them wrong with his very successful adaptation of J.R.R. Tolkien's classic novel. So are there any books that are 'unfilmable'? That's what this article discusses.