Madonna put on a free concert on Copacabana beach on Saturday night, 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 with her 1998 hit “Nothing Really Matters.” Huge cheers rose from the buzzing, tightly packed crowd, pressed up against the barriers.

Others held house parties in brightly lighted apartments and hotels overlooking the beachfront. Helicopters and drones flew overhead, and motorboats and sailboats anchored off the beach filled the bay.

“Here we are in the most beautiful place in the world,” Madonna, 65, 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."

Madonna performed her classic hits, including “Like A Virgin” and “Hung Up.” For the introduction to “Like A Prayer,” her head was completely covered in a black cape, a rosary gripped in her hands.

The star paid an emotional tribute to “all the bright lights” lost to AIDS as she sang “Live to Tell,” with black and white photos of people who died from the illness flashing behind her.

Later, she was joined on stage by Brazilian artists Anitta and Pabllo Vittar.

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

An estimated 1.6 million people attended the show, G1 reported, citing Rio City Hall's tourism agency. That is 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.

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.”

Flags with “Madonna” printed against a background of Copacabana's iconic black and white waved sidewalk pattern hung from balconies. The area was packed with street vendors and concert attendees kitted out in themed T-shirts, sweating under a baking sun.

“Since Madonna arrived here, I've been coming every day with this outfit to welcome my idol, my diva, my pop queen,” said Rosemary de Oliveira Bohrer, 69, who sported a gold-coloured cone bra and a black cap.

“It's going to be an unforgettable show here in Copacabana,” said Oliveira Bohrer, a retired civil servant who lives in the area.

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

City Hall produced a report in April estimating that the concert would inject 293 million reals (USD 57 million) into the local economy. Hotel capacity was expected to reach 98 per cent in Copacabana, according to Rio's hotel association. Fans hailing from across Brazil and even Argentina and France sought out Airbnbs for the weekend, the platform said in a statement. Rio's international airport had forecast an extra 170 flights during May 1-6, from 27 destinations, City Hall said in a statement.

“It's a unique opportunity to see Madonna, who knows if she'll ever come back,” said Alessandro Augusto, 53, who flew in from Brazil's Ceara state — approximately 2,500 km (1,555 miles) from Rio.

“Welcome Queen!” read Heineken ads plastered around the city, the lettering above an image of an upturned bottle cap resembling a crown.

Heineken wasn't the only company seeking to profit from the excitement. Bars and restaurants prepared “Like a Virgin” cocktails. A shop in the downtown neighborhood famed for selling Carnival attire completely reinvented itself, stocking its shelves with Madonna-themed costumes, fans, fanny packs and even underwear.

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 3,200 military personnel and 1,500 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 4 million fans and was the biggest free rock concert in history, according to Guinness World Records.

Many of those spectators also came to see Rio's fireworks show, though, so a more fitting comparison might be to the Rolling Stones in 2006, which saw 1.2 million people crowd onto the sand, according to Rio's military police, the newspaper Folha de Sao Paulo reported at the time.

Ana Beatriz Soares, a fan who was at Copacabana on Saturday, said Madonna has made her mark across the decades.

“Madonna had to run so that today's pop artists could walk. That's why she's important, because she serves as an inspiration for today's pop divas," Soares said.

"And that's 40 years ago. Not 40 days, 40 months. It's 40 years,” she said.