PARIS (AFP) -- Plans for the opening ceremony at the Paris Olympics -- the first time a Summer Games will start outside a stadium -- have been a closely guarded secret.

Here is what we know about the concept, the artists and the music:

What's the concept?

Instead of using the main athletics stadium for the opening parade, as is customary, organizers have moved the event outside and into the heart of the capital -- in keeping with their motto "Games Wide Open."

Around 6,000-7,000 athletes are set to sail down a six-kilometer stretch of the river Seine from the Austerlitz bridge in the east to the Eiffel Tower, on 85 barges and boats.

Up to 500,000 people are set to watch in person from specially built stands, where tickets have sold for up to 2,700 euros ($2,900), on the river banks for free, and from the overlooking balconies and apartments.

"Organizing a ceremony on the Seine is not easier than doing it in a stadium... but it has more punch," chief organizer Tony Estanguet told AFP earlier this month.

Because of the size and complexity of the parade, it has never been rehearsed in full.

What about the entertainment?

The show has been designed by theatre director Thomas Jolly, a 42-year-old prodigy known for the hit rock-opera musical "Starmania."

He brought on board a creative team that includes the writer of the French TV series "Call My Agent," Fanny Herrero, as well as best-selling author Leila Slimani and renowned historian Patrick Boucheron.

The show has been split into 12 different sections, with around 3,000 dancers, singers and entertainers set to be positioned on both banks of the river, the bridges and atop nearby monuments.

A tribute to Notre-Dame Cathedral, in the process of being renovated after a devastating fire in 2019, is guaranteed, possibly with dancers on its scaffolding.

Starting at 07:30 p.m., two thirds of the ceremony will take place in daylight -- the weather forecast shows cloudy skies and moderate temperatures -- and will end with a light show.

The music will be a mix of classical, traditional 'chanson francaise', as well as rap and electro.

Franco-Malian R&B star Aya Nakamura is set to be one of the star performers despite criticism from far-right politicians, including Marine Le Pen, who suggested in March that an appearance by her would "humiliate" France.

Lady Gaga and Celine Dion have both been spotted in Paris, fueling rumors they will appear.

French electro superstars Daft Punk have turned down an invitation to play while globe-trotting French DJ David Guetta has been overlooked -- much to his irritation.

What's the message?

Asked to sum up his message last week, Jolly said it was "love."

Despite the risk of irking conservatives, he said his work would be a celebration of cultural, linguistic, religious and sexual diversity in France and around the world.

"I think the people who want to live together in this diversity, this otherness, are much more numerous, but we make less noise," he told AFP.

It is fair to assume it will be nothing like the widely panned retro-styled opening ceremony of last year's rugby World Cup, which featured a succession of French clichés from baguettes to berets and the Eiffel Tower.

And don't expect a three-hour tribute to French greatness to rival the nationalistic pageantry seen at the Beijing Games in 2008.

"The opening ceremony in Beijing in 2008 was exactly what we did not want to do," Boucheron told Le Monde newspaper.

What will be the big moments?

With so much still under wraps, it's hard to predict.

The performance by Nakamura, after so much controversy about her role, will be a major moment soon after the parliamentary elections that saw the anti-immigration far-right gain a historic 143 seats in the national parliament.

Jolly has strongly hinted that a submersible or submarine will emerge from the waters of the Seine at some point.

The identity of the final torch holder who will light the Olympic cauldron in the gardens in front of the Louvre museum also remains unknown, although triple gold medal-winning sprinter Marie-Jose Perec is among the leading contenders.

The biggest moment of all might simply be the end if everyone gets home safely.

The ceremony has given French police cold sweats ever since it was unveiled in 2021 because of the difficulty of securing so many people over such a vast urban area.