The Prix De l’Arc de Triomphe, held every fall at the Longchamp course in Paris, is one of the world’s longest running and most prestigious horse races and is rivaled only by Royal Ascot in terms of glamour, though it doesn’t get as much publicity. First run in 1920, it has long been known as the world’s richest race, and nowadays carries a purse of €5 million. Of course its Parisian setting means the event has always had plenty of panache, and the thoroughbreds watching the race are as closely scrutinized as the ones in it. “In a French horse race the horses run a poor third to the pretty girls and latest fashions,” LIFE reported in 1939. “People go, not so much to see the races, as to see each other, to bet and get a glimpse of the season’s fanciest clothes…. The center of the stage is held by the spectators, not the horses.”

10 years later little had changed when the magazine revisited Longchamp, despite the privations of the war. Racing had continued even during the conflict as the course was a favorite with status-obsessed German officers. Well insulated from worldly cares, the old line aristocrats in their silk hats and striped trousers epitomized the indefatigable elegance of the upper classes, who had been holding court at Longchamp since 1857 when Emperor Napoleon III and his wife Eugénie sailed down the Seine on their yacht to attend the opening race. However it wasn’t just the ancien régime who turned out; some 100,000 people were there to witness Coronation win the Arc that year. Here’s a long-lost set of photos from the magazine showing that some things never go out of style. Vive La France.