Ah, Casablanca. The little movie that could. It's one of those 'classics' everyone talks about that you force yourself to watch as part of your education in film, never expecting it to be nearly as good as everyone says, let along to be any fun. Yet that was exactly my experience when I saw the film for the first time about 18 months ago. With that said, I'm not going to attempt any kind of academic analysis of the film here. So much has been written about Casablanca and its stars that anything I could say in that capacity would be seem just a tad redundant. What I thought I'd share instead is how the film affected me as just a plain old movie buff, and what made it worthy of the No. 10 spot.

To me, Casablanca is very fantasy-like. The city itself is such an exotic, ancient place seemingly locked away from the rest of the world that and filled with any kind of character you could imagine: less a hideaway for crooks and lowlifes as much as it is the place where crooks and lowlifes are born. For the audience, it's an enclosed space - we never enter it, and we never leave it. As such, the film offers a particular idea of what Casablanca is, rather than granting it much in the way of real-world geography or politics. It's freedom and a prison, haven and hovel, wealth and hardship, life and death, and Rick's saloon stands at the centre of it all; a filter through which Casablanca's cosmopolitan population must inevitably pass. The character of Rick is a plum role - he's a freedom fighter, hopeless romantic and hardened tough guy, and Humphrey Bogart was simply born to play him. It's really all Bogie's film, but through the stern demeanour and "I don't risk my neck for nobody" attitude, there's still plenty of room for the rest of that fantastic cast to shine.

As well as the engrossing otherworldliness of the city these characters occupy, Casablanca (still) has one of the greatest screenplays ever written. It's not noir, but contains plenty of the same crackling dialogue and a proto-existentialist attitude; it's not a romance, but it portrays one of the most convincing love triangles ever committed to film; and it's not a war film, but contains more than enough patriotic and idealistic fever to go around. All of which is ironic when you realise there wasn't a finished script when they started filming and no one knew how it would end. It was based on an unpublished play, but the film script was always a work in progress, with all the usual changes such an adaptation entails. Ingrid Bergman, for example, had no idea which of her character's two love interests she'd end up with, and director Michael Curtiz's advice was to simply play it down the middle. In most cases, such a flying-by-the-seat-of-your-pants approach would result in a huge mess, but here everything (and I mean everything) comes together so magnificently and coherently. In Bergman's case, it makes a token female love interest into a fully realised character, since she is truly torn between two men, compelled to love both equally until that final, memorable scene.

And then there's that song. Rarely has a film utilised a piece of music so successfully: 'As Time Goes By' becomes a thematic touchstone of the film, integrated into the score as well as a piece of diegetic music that introduces characters, establishes conflict, and aids in resolution. It may have become something of a cliché, along with much of the script's best moments, but there's a reason why these things stay in the popular memory.

For me, Casablanca is what storytelling for film is all about. When you don't necessarily have to be interested in the subject matter because you're so fascinated by the way it all comes together so perfectly balanced. It's this combination of writing, directing and acting that makes Casablanca such an engaging film and goes a long way to explaining its longevity and continuing popularity.