Around six o'clock every evening during the Cannes Film Festival, the upmarket Riviera town comes to a standstill.
With 30,000 visitors doubling the population for the festival, Cannes suffers from M50-style gridlock throughout the event. Then the pedestrians hit the streets in early evening, swarming the Festival Palais that looms over the seafront.
Long established as the world's biggest, most important film festival, Cannes lays on the pomp and ceremony twice a night, when the officially invited movies have their gala screenings inside the Palais, and the bigger the movie, the bigger the crowds of locals and tourists gathered outside.
Tomorrow's main movie is very big indeed, the world premiere of Star Wars Episode III: Revenge of the Sith, and thousands will throng the Palais area to catch a glimpse of director George Lucas and his cast - Hayden Christensen, Natalie Portman and Samuel L Jackson - going up the red-carpeted steps.
The organisers have the procedure down to a fine art. A passage is cleared for the gleaming limos discharging their chicly attired passengers at the entrance. Tenue de soiree (evening dress) is mandatory at every one of the Palais gala screenings, and patrolled by fashion police. It is not at all uncommon for guests deemed to be wearing the wrong shoes, for example, to be sent back down the steps like a humiliated Big Brother evictee.
Gendarmes form a guard of honour on both sides of the steps as the slow procession of the red carpet begins - and the event turns into the Cannes Frock Festival before slews of photographers, who also have to be in evening dress. This is regarded as such an important photo opportunity that it's irresistible to people cashing in on the huge international media presence at the festival (around 5,000 this year) - even if they haven't got a film in the official selection.
In 1993, at the gala for Mike Leigh's low-budget Naked, Arnold Schwarzenegger, in Cannes to plug some action movie, stole the thunder of Leigh and his cast by grinning and waving his way up the steps - and promptly slipping out a rear entrance as soon as he entered the Palais.
A celebratory party follows each gala screening. Some are relatively modest. When The General was screened in 1998, winning John Boorman the best director prize, the party was relatively modest and held in the only Oirish bar in Cannes.
Other parties can cost more than many of the movies in the festival. The 1993 screening of Raining Stones - Ken Loach's socially concerned picture of a working-class man struggling to pay for his daughter's First Communion dress - was followed by an extravagant bash at a villa up in the hills, where the champagne flowed and the tables groaned under gourmet fare.
And that pales in comparison with the excesses of the Hollywood studios at the festival.
For decades, Cannes has walked a tightrope between art and commerce. People have to wear evening dress to watch low-budget movies about racism, torture, ethnic cleansing and social deprivation. High art is the aspiration of the festival competition, but if a megastar is available to walk the red carpet, a prestigious out-of-competition slot becomes available - as when Madonna generated a media frenzy with the documentary In Bed With Madonna, or when Far and Away closed the festival and Tom Cruise and Nicole Kidman did carpet duty.
It works both ways. Even the formerly publicity-shy Woody Allen is now a regular on the festival circuit. He was back in Cannes on Thursday for the world premiere of his new movie, Match Point, joined on the carpet by its handsome Irish actor Jonathan Rhys Meyers and his equally eye-catching US co-star, Scarlett Johansson, and securing front-page coverage around the world.
Away from the red carpet, Paris Hilton - the hotel heiress famous for being famous and a sexually explicit video posted on the Internet - is doing a beach photo call today to plug her new movie, Pledge This! - "the most hilarious, outrageous and sexy comedy", according to its hyperbolic publicity material.
The Cannes beach has been de rigueur for photo shoots since a breast-baring British starlet got up close and personal with Robert Mitchum for the cameras back in 1954 - even though the beach has been topless for decades.
For variety this week, Kiera Chaplin, granddaughter of Charlie, was lined up to wear "not a great deal" and ride a horse along the Croisette to hype up Lady Godiva: Back in the Saddle, which has yet to start shooting.
This year, and not for the first time, a movie showing outside the official selection at Cannes is the link to the hottest ticket of the festival. Stephen Chow's exuberant martial arts movie, King Fu Hustle, a huge hit in Asia, will be followed by a lavish party tonight, hosted by Sony and MTV at Le Palais Oriental. The invitation advises that it runs from 10pm to 6am. At festival time, Cannes never sleeps.
• Michael Dwyer continues his reports from Cannes on Tuesday's Arts page