Madonna has put on a free concert on Copacabana beach, turning Rio de Janeiro’s vast stretch of sand into an enormous dance floor teeming with a multitude of her fans.

It was the last show of The Celebration Tour, her first retrospective, which kicked off in October in London.

The “Queen of Pop” began the show on Saturday with her 1998 hit Nothing Really Matters. Huge cheers rose from the buzzing, tightly packed crowd, pressed up against the barriers. Others looked on from brightly lighted apartments and hotels lining the beachfront. Helicopters and drones flew overhead.

“Here we are in the most beautiful place in the world,” Madonna told the crowd. Pointing out the ocean view, the mountains and the Christ the Redeemer statue overlooking the city, she added: “This place is magic.”

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Rio spent the last few days readying itself for the performance.

Rio’s City Hall predicted 1.5 million spectators, more than 10 times Madonna’s record attendance of 130,000 at Paris’ Parc des Sceaux in 1987.

Madonna’s official website hyped the show as the biggest ever in her four-decade career.

In recent days, the buzz was palpable. Fans milled outside the stately, beachfront Copacabana Palace hotel, where Madonna is staying, hoping to catch a glimpse of the pop star.

During the sound check on the stage set up in front of the hotel, they danced on the sand.

Fans flocked to the famous beach for Madonna’s performance. Photo: WireImage/Getty

By midday Saturday, fans crowded in front of the hotel. A white-bearded man carried a sign saying, “Welcome Madonna you are the best I love you.”

Eighteen sound towers were spread along the beach to ensure that all attendees can hear the hits. Her two-hour show started at 10.37pm local time, nearly 50 minutes behind schedule.

Organisation of the mega-event was similar to New Year’s Eve, when millions of people gather on Copacabana for its fireworks display, local authorities said.

That annual event often produces widespread thefts and muggings, and there was some concern such problems might occur at Madonna’s show.

Rio state’s security plan included the presence of 3200 military personnel and 1500 civilian police officers on stand by.

In the lead-up to the concert, Brazil’s navy inspected vessels that wished to position themselves offshore to follow the show.

A number of huge concerts have taken place on Copacabana beach before, including a 1994 New Year’s Eve show by Rod Stewart that drew more than four million fans and was the biggest free rock concert in history, according to Guinness World Records.

-AP