The biggest Met Gala secrets revealed in Anna Wintour's new biography

• The Metropolitan Museum of Art Costume Institute Gala benefit called the Met Gala is May 2.
• The party brings out celebrities, musical superstars, and other Hollywood heavyweights.

Hosted by Anna Wintour since 1995, the annual Metropolitan Museum of Art Costume Institute Gala benefit, known popularly as the Met Gala, brings out the biggest names in Hollywood.

Generally considered the Super Bowl of fashion or the East Coast Oscars, the fashion event, which raises funds for the museum, is traditionally held on the first Monday in May. It has become New York's biggest party of the year under the stewardship of Wintour, who is Vogue's editor-in-chief and the artistic director of its parent company, Condé Nast.

Assembling the party takes a full year's worth of work from careful planners and skillful negotiators that have honed their skills over decades. Together, they corral celebrities into using ther star power — and occasionally their checkbooks — to promote the cause.

"Anna," a new biography of Wintour written by fashion journalist Amy Odell, tells readers some of what it takes to get stars on the Met Gala stairs and some of what happens once they disappear behind the museum's doors.

Here are six juicy secrets Odell reportedly uncovered in the upcoming page-turner, out on Tuesday, May 3.

Rihanna was paid $1 million to perform in 2015

The billionaire pop star and Fenty founder leapt off the red carpet and onto the stage where her performance commanded a stiff price tag "after a long negotiation," Odell writes.

Beyoncé and Jay Z were flown in on a private jet that cost $100,000

The Carters joined in on the fun fresh from the "clear port" after being flown into town to attend the affair. "For the biggest stars, the Met had spent more than $100,00 on a private jet to bring them to the party," writes Odell.

According to Odell's sources, it was a sound investment, as the museum nets millions of dollars annually from the function.

Kim Kardashian was asked to sit down in her 2019 gown, but she was physically unable to do it

Wintour does not only vet the guest list — she pays attention to guests' positioning once inside the party.

Lisa Love told Odell in an interview for the book that Wintour repeatedly requested that Kardashian be seated in her 2019 Thierry Mugler dress (designed to fit that year's "camp" theme). Love said she had to explain that Kardashian physically couldn't sit.

George Clooney and Amal Clooney were given private rooms

The couple "requested and were given a private bar" where they could relax away from the other guests at the Met Gala. "The museum also had its bookstore outfitted with upscale rental furniture for Amal so she had a place to change clothes," Odell writes.

Others were given private quarters as well

The Clooneys were not the only ones who required a bit of privacy. Despite the infamous group bathroom selfies that emerge the day after the gala each year, "the museum is dotted with greenrooms for various stars," including Sarah Jessica Parker.

And space is not the only luxury reserved solely for preferred partygoers.

Diet Coke was locked away for Karl Lagerfeld

"Karl Lagerfeld attended, and the Met had to work with his team to procure his desired beverage, Coca Cola Light, which was locked away in an office in the museum for protection," Odell writes.

You can learn more about Wintour and the Met Gala in "Anna," which will be available for purchase on May 3.