Fully enclosed, climate-controlled, self-sufficient, with a resident population of workers in a variety of novelty uniforms and specialist vehicles, all run by invisible controllers who monitor everybody round-the-clock - these places are modern-day city states, benevolent dictatorships which can only too easily turn nasty. Yet the best examples fully embody Le Corbusier's famous definition of architecture as "the masterly, correct and magnificent play of masses brought together in light."

Consider, from recent times Norman Foster's Stansted and Hong Kong; Kisho Kurokawa's Kuala Lumpur; Paul Andreu's Paris Charles de Gaulle in all its phases; and Renzo Piano's Kansai. Richard Rogers' Heathrow T5 and new terminal at Madrid's Barajas also look promising. Go back to the start of the jet age, and you find Eero Saarinen's Washington Dulles and TWA terminal at JFK, plus Vilhelm Lauritzen's Copenhagen. From the propeller-driven 1930s, you have Ernst Sagebiel's classical Berlin Tempelhof; the Art Deco of Liverpool Speke and New York's La Guardia; and the streamlined "moderne" of Paris Le Bourget, now an air museum. These are all architecture of the highest order: Paris Charles de Gaulle, for instance, remains a huge achievement despite the deadly mystery of a small new part of it collapsing earlier this year.

The idea of the airport as a place of potential splendour and fruitful encounter is fully understood by Stephen Spielberg. His latest blockbuster film "The Terminal" (on release from next Friday September 3) stars Tom Hanks as the bewildered but resourceful Viktor Navorsky, a visitor forced to live at New York's JFK airport for months because his country has become politically unacceptable while he was in flight. Spielberg makes his airport as much of a character as any of the humans that inhabit it. It has to be: all the action, but for a brief section at the end, takes place inside it. Like the exhibition-centre Paris of Jacques Tati's "Traffic", or for that matter the Wessex of Thomas Hardy's novels, the backdrop becomes an intrinsic part of the action.

Spielberg's JFK is not the real place or even a close replica of one of the terminals there, but a set built at huge expense in a hangar in Palmdale, California. Production designer Alex McDowell produced a full-size, fully-operational terminal derived from a selection of American and European airports. It is deliberately made just slightly more terminalistic than the real thing. Its surfaces are just a bit shinier and more brittle, there are more escalators and flight-information screens, a state-of the art Dutch-designed airport signage system, a veritable casbah of familiar shops and cafes, and of course there is the inevitable section undergoing rebuilding, a parallel universe for the characters who inhabit the place.

The interesting thing about Spielberg's terminal is that - in order to function convincingly - it had to be built as a real, three-storey building rather than as a flimsy set. Complete with 60,000 feet of granite floors and 35 familiar retailers, some with real Starbucks-style staff, it took 20 weeks and 200 workers to build. No virtual reality for Spielberg here: what you see, apart from spliced-in scenes of planes pulling up outside, is physical actuality. As love interest Catherine Zeta-Jones remarked: "It even smelled like an airport." Spielberg lights it such that at first it seems hard and alien, and gradually becomes a warmer, more human place. They should try him on the real thing.