For 25 years, the Serpentine Pavilion has celebrated architecture on the grounds of the Serpentine Gallery in Hyde Park London, England. In 1994, the Serpentine Gallery summer party was where Princess Diana famously debuted her “Revenge Dress,” and in the years since, it has become a mainstay on the summer calendar for British royals, celebrities, and more A-Listers.

Princess Diana Archive // Getty Images

Last night, Cate Blanchett and Isha Ambani were among the co-hosts of the soirée. “The Serpentine Summer Party is unique. I so enjoyed it, a wonderful gathering of cultural contributors in a casual, intimate setting,” Ambani told Hello.

“Supporting our cultural institutions and their power to illuminate the world at large and our place within it is of paramount importance,” Blanchett said in a statement. “I’m honored to cochair the Serpentine party and its summer festivities where so many creative forms —architecture, performance, music, science and digital narratives — intersect.”

Lady Amelia Windsor, who is a regular attendee, said the annual party is “a great place to admire outfits,” adding, “I love that [this party] is outside and that you get to appreciate art.” Here, see the best photos of royals and celebrities at the 2025 Serpentine Summer Party: