Kim and Kanye step out in style.

Screaming fans have mobbed a 16th-century fortress in Florence as it played host to celebrity royalty Kanye West and Kim Kardashian and the hundreds of guests gathered for their sumptuous wedding party.

The 33-year-old reality TV star and her 36-year-old rapper beau flew into the historic Italian city aboard private jets, after kicking off their marathon wedding celebrations with a party in the Versailles palace on Friday night.

As their guests started to arrive in the city, nestled in the Tuscan countryside, fired-up fans filled the roads around Fort Belvedere, peering into every blacked-out car in the hope of spotting a favourite celebrity.

“Justin, Justin”, one young fan yelled, convinced the Canadian singer Justin Bieber might be inside.

“We’re here because of Kim, because it is her wedding, but also for Justin,” a girl called Chiara said.

Others were drawn by rumours that superstars Beyonce and Jay Z would be among the 1600 guests invited to party with the couple, in the historic fort built by the Medicis.

A source at Florence city hall said Kanye and Kim would be married by a Protestant minister on Saturday — despite reports that the couple, who have a daughter, were wedded in May in a civil service in California.

Vanity Fair has released aerial pictures of the fort, showing a white structure in the shape of a church, with an altar and rows of chairs at the ready.

On Friday night the limelight-loving couple and their entourage were partying in Versailles, the favourite palace of France’s “Sun King” Louis XIV, the superstar attention seeker of his day.

Wearing a white gown whose deep-plunging neckline defied the laws of motion, Kardashian and her husband-to-be welcomed several hundred guests to celebrations that featured horses and riders with huge feathers in their hats, musketeers in wigs and drum rolls.

West and Kardashian settled on a private party in the prestigious chateau outside of Paris after they were told they would not be able to marry there in January.

But Versailles was a mere exclusive aperitif to the huge fete in Florence.

Renting out the fortress normally used for exhibitions stirred up some controversy but the city promised that most of the 360,000 euros ($A540,000) paid by West and Kardashian would be used for restoration work.

After months of suspense, the festivities were gradually revealed throughout Friday according to a carefully orchestrated plan by the Kardashian clan, who became famous through reality TV and were clearly eager to make this the marriage of the year.

The marathon wedding could earn them up to $US21 million ($A22.72 million) thanks to sponsors and through the sale of exclusive photos of the ceremony, according to press reports.