Didier Ludot got things started on Sunday with a soirée for the Christian Dior retrospective he organized in the Palais Royal, the 376-year-old former home of Cardinal Richelieu and current location of Ludot's vintage store, as well as a future Marc Jacobs boutique. "Not since the eighteenth century has there been a party here," said the bespectacled shopkeeper. "It's usually impossible to close the garden, but the minister of culture liked the project…" A late-running Yohji Yamamoto show on the Left Bank and the damp, rainy night prevented fashion's boldfacers from hitting the scene, but a pair of Roger Vivier-designed pumps worn by Marlene Dietrich had the flashbulbs popping.

On Thursday, fire codes were broken at the subterranean lair that is the eighth arrondissement's Régine's club. Waiters carried buckets full of ice, Champagne, and fireworks over the heads of Vogue's Hamish Bowles, Vanity Fair's Elizabeth Saltzman Walker, and Steve Zissou's Wes Anderson to a table in the back where Stella McCartney was celebrating her first collection since taking time off to have a baby. "I'm so relieved it's over," said the designer as she poured glasses for pals like Jeff Koons, whose paintings appeared as prints on her dresses. "But you'll notice that I don't have a drink." Her husband, the handsome (and, some say, remarkably Sir Paul-resembling) Alasdhair Willis, rectified that with a brimming flute. Sweet, but not as sweet as the speech he had given at the private dinner beforehand: "It was so wonderful," she said. "I wanted to cry."

Exactly a week after it all began, Louis Vuitton threw a post-show bash at the Petit Palais in honor of its new store—the world's biggest L.V.—on the Champs-Elysées. In one wing of the seventeenth-century museum, a Vanessa Beecroft installation turned partygoers into amateur paparazzi—this time, her girls wore strawberry-color afros and matching, well, you know. Another wing was converted into a dance club with tunes courtesy of Pharrell Williams, in Jacob the Jeweler bling reminiscent of last season's Vuitton crochet chain necklace. Outside, Winona Ryder, Natalia Vodianova, and Jade Jagger worked the massive oval courtyard, its pillars illuminated in cobalt neon. Negotiating the crowds at the makeshift bars, where Veuve Clicquot flowed like the fountain at nearby Place de la Concorde (thank you, M. Arnault), was Marc Jacobs, a bit overwhelmed by the spectacle. "It's like Las Vegas," he said. "But I mean that in a good way. It's just so grand."

Meanwhile, back in New York… U2, no strangers to doing things on a grand scale, drew a sizeable herd of fans to the launch of their new week-long photo exhibit, U2 & i, at the Stellan Holm Gallery. As the likes of Orlando Bloom, Kate Bosworth, and Amanda de Cadenet sipped inside the space on red wine in plastic cups, the crowd—which included a man who mimicked Bono style down to the Bulgari sunglasses—spilled out onto the street and clogged traffic on 24th. The group's long-standing personal photographer Anton Corbijn temporarily stole the spotlight from the lead singer, who, along with guitarist the Edge, was on hand to recommend artwork to such buyers as Anne Dexter Jones. As Corbijn surveyed the glossy images, depicting the Irish rockers over the span of 22 years, he remarked, "Yeah, I'm happy with it," before taking another scan: "But it's a little Bono-heavy."

—Nicole Phelps (Paris) and Sarah Cristobal (New York)