Think of Taxi Driver and its unforgettable depiction of the teeming nightlife in Manhattan's Hell's Kitchen district. Or the Rome of Bicycle Thieves. Or Los Angeles in Michael Mann's Heat. Or the Iranian villages in the films of Makhmalbaf. In each case the setting is not just the world out of which the characters grow, but also, somehow, the reason why the film exists.
This is not always the case with great movies. The oft-quoted example is Casablanca, not a foot of which was shot on location. Studio filming lent it a seductive veneer. The flaws and accidents of real life were nowhere to be seen.
Conversely, real locations can generate vitality. Our eyes dart around the screen, fixing on the details of street life and real faces. Roland Barthes used the word "punctum" to describe the piercing effect that such unplanned photographic detail can have.
All this is relevant again because of two new trends in mainstream cinema. The first is "runaway" production, where cities like Toronto are used to stand in for Manhattan to save money. In 1990, no Hollywood movies with budgets over $25m were filmed abroad. In 1998, 24 were, and the figure is rising (the number of smaller-budgeted runaway films nearly doubled in the same period). The state of California reckons that nearly $10bn of its $34bn film and television industry is being lost as producers go elsewhere. Anthony Minghella's Cold Mountain was a particular bone of contention last year when it used Romania to stand in for North Carolina, thus slashing its $150m budget to around $80m.
The second trend is just as significant. The newest instalment in George Lucas's Star Wars saga was shot almost entirely against green screens, with computer-generated locations "added in post," as was the recent Jude Law vehicle Sky Captain and the World of Tomorrow. Neither of these films have radically new content - they derive from serials like Buck Rogers and city movies such as Metropolis - but when you add together the influence of CGI backgrounding and runaway production, you begin to reduce the role that real locations play in the cinema.
The obvious response to this is concern that films are getting less authentic. But it is hard to get worked up about authenticity in cinema. The opening 20 minutes of one of Roman Polanski's best films illustrates a more interesting issue. In The Tenant (1976), the main character Trelkovsky, played by Polanski himself, is looking for an apartment to rent. He arrives at a run-down 19th-century courtyard tenement in Paris. The landlady closes a window to get rid of him, but he opens it again and persists. So she brings him upstairs, fiddles with the lock, enters the gloomy flat and lets him in. She opens French windows to show him where a previous occupant fell. He moves in and explores the place, opening a wardrobe where he finds a dress, looking out into the courtyard to see who is using the toilet on the landing opposite.
The apartment in The Tenant fascinates us because the actors interact with it. All that opening and closing of windows and wardrobes make it a real place, full of noises and mysteries. And looking out across the courtyard or up the stairwell establishes the sightlines of the building, who can see whom. The theme of the film is how a place can drain the life out of a person. It becomes vivid as Trelkovsky becomes absorbed into its secrets. In the era of the green screen, with its post-hoc backdrops, actors can't interact with the scenery as they do, brilliantly, in The Tenant.
But Trelkovsky's apartment in the film was only a very carefully designed and dressed set: the location does not need to be real to be alive. Still, sets and locations can be alive in different ways, and it is the interactions which count. In Bernardo Bertolucci's The Spider's Stratagem of 1970, a son returns to the town of Tara where his father, Athos Magnani, is worshipped as an anti-Mussolini hero. Magnani was nothing of the sort and the town has been in a state of somnambulant denial since his death. To depict this dream-like state, Bertolucci filmed the whole movie in Sabbionetta in Emilia-Romagna, an extraordinary colonnaded town. Bertolucci has real villagers stand statically as Magnani fils runs past them through motionless piazzas. The first time we meet the main female character, who was in love with the father and will soon fall for the son, she is standing still in the distance in a garden. The camera sweeps right to find her and, as if brought to life by its motion, she suddenly walks forward at its pace.
If the Polanski example shows that actor interactivity and sightlines are key elements in rendering a space alive in a film, the Bertolucci movie reminds us that sets and locations can be alive in different ways. In the end, the creative question for filmmakers is not whether Toronto looks like Manhattan or whether Jude Law can make us believe in the CGI world behind him. Rather it is how to make sure that the settings for their films are not passive. The set sucks the life out of Trelkovsky. The son of Athos Magnani wakes up the town which he visits. The locations in the best films do something to their characters or, even more interestingly, the characters do something to their locations. The relationship between the two is what fascinates us.