PARIS (NYTimes) - On Monday night, on one of those spectacular Paris summer evenings when the light shimmers off every surface and the sun doesn't set until around 10, hundreds of fashionably dressed people gathered in the garden of the Musée des Art Décoratifs, enjoying Champagne and hors d'oeuvres as a newly shorn and platinum blond Cara Delevingne looked on from above, standing in the open French doors of a second-floor reception room.

Although the guests (who included actor Robert Pattinson and model Bella Hadid) mingled among topiary versions of now-classic fashion designs, few people seemed to actually make it inside to the exhibition itself: Christian Dior: Couturier du Réve, a retrospective of 70 years of the house of Dior.

And that's too bad, because the show is a stunner.

Billed as the largest fashion exhibition ever staged by the museum, the show, which officially opens on Wednesday and runs through Jan 7, features more than 300 haute couture gowns from the seven designers who led this fashion house, from Christian Dior himself to Maria Grazia Chiuri, who presented her second couture collection earlier on Monday.

Each of the designers who followed Dior and who preceded Chiuri have their own exhibition rooms: Yves Saint Laurent, Marc Bohan, Gianfranco Ferré, John Galliano and Raf Simons. And each grouping offers a bit of revelation, from the awe-inspiring Trapeze collection by Saint Laurent, done when he was just 21 years old, to the way that Simon both honoured and modernised the classic Dior look when he showed his first collection in 2012.

But perhaps the biggest surprise is the reverence given to the Galliano years. The House of Dior has had a understandably complicated relationship with the Galliano era ever since the designer was fired in 2011 after making drunken anti-Semitic comments in a Paris bistro. But here the genius of his work - there is no other word for it - is given its due, and one is again reminded how the Galliano Dior shows were typically the most anticipated of couture week.

But it all comes back to Dior himself. And his designs, placed strategically throughout the show, are a reminder of what a revolutionary figure he was in the fashion world and how the Bar Jacket - which holds a place of pride at the exhibition's entrance - remains both an inspiration and a challenge to all who have come after him.