People.com Entertainment Movies Inside Leonardo DiCaprio's Star-Studded Charity Auction with Kate Winslet, Madonna and More Leonardo DiCaprio Foundation's fourth annual fundraising gala took place in St. Tropez, France on Thursday night By Jodi Guglielmi Jodi Guglielmi Instagram Twitter Writer-Reporter, PEOPLE People Editorial Guidelines Published on July 27, 2017 11:09 AM Share Tweet Pin Email 01 of 09 Leonardo DiCaprio and Kate Winslet Anthony Ghnassia/Getty Images for LDC Foundation The Titanic costars reunited at the event — and auctioned off an extra-special prize. One lucky bidder was given the chance to have dinner with the longtime friends sometime in October or November at a place of their choosing in New York City. 02 of 09 Leonardo DiCaprio Venturelli/Getty Images for LDC Foundation DiCaprio spoke on stage at the annual event, hosted on July 26 in St. Tropez, France. This year’s auction included works from renowned artists like Rashid Johnson, Sanya Kantarovsky, Adrian Genie, Damien Hirst, Jonas Wood and even Paul McCarthy. Proceeds from the gala and auction will support the Leonardo DiCaprio Foundation's environmental causes. While $30 million has been raised so far, the auction continues online. Following last night’s preview, bidding will begin on August 10 and end on August 23. 03 of 09 Madonna Venturelli/Getty Images for LDC Foundation Madonna performed as a surprise guest. She later posted a video of her performance to Instagram, captioning the post, “Such an honor to be here supporting Leo’s foundation and doing what we can to save Planet Earth!” 04 of 09 Leonardo DiCaprio and Tobey Maguire Victor Boyko/Getty Images for LDC Foundation It's no surprise the Spider-Man star showed up to support DiCaprio — the two have been friends for over 30 years. 05 of 09 Leonardo DiCaprio and Sean Penn Anthony Ghnassia/Getty Images for LDC Foundation Along with Penn, the star-studded gathering included Prince Albert II of Monaco, Penn's ex Madonna, Uma Thurman, Jared Leto, Cate Blanchett, Marion Cotillard, Kate Hudson, Edward Norton and Tom Hanks. 06 of 09 Leonardo DiCaprio, Kate Winslet and Billy Zane Billy Zane/Instagram Titanic’s love triangle is back together again! The former costars posed for a photo together inside the event. “Gangs back together. Now we’re saving icebergs. Go figure,” wrote Zane on Instagram, referencing LDF’s environmental protection work. The occasion also happens to mark the film’s twentieth anniversary. 07 of 09 Kate Winslt Anthony Ghnassia/Getty Images for LDC Foundation Winslet also helped auction off some Titanic memorabilia — including a signed life jacket from the film. 08 of 09 Leonardo DiCaprio and Madonna Victor Boyko/Getty Images for LDC Foundation Following her performance, DiCaprio and Madonna posed for a photo together. 09 of 09 Lenny Kravitz, Leonardo DiCaprio and Madonna Anthony Ghnassia/Getty Images for LDC Foundation Kravitz also performed, taking the stage later in the evening with Madonna and DiCaprio dancing and singing along behind him.