London - London 2012 organisers on Saturday promised an emotional celebration to bid farewell to the Olympics and Paralympics, as the curtain falls on a summer of elite sport in the British capital.
Coldplay will headline Sunday evening's show, entitled "Festival of the Flame", which will draw heavily on Britain's rich history of cultural, musical and seasonal festivals, artistic director Kim Gavin told a news conference.
"The only narrative we have got is that we are taken through the seasons to the Coldplay music. It's not just a concert and we are not just looking at Coldplay," he added.
"We have got fantastic visuals and amazing stunts going on. It's a celebration and recognition of people coming together... What we have tried to do is bring something that feels very raw.
"We have taken the flame, being part of and representing the human spirit that brings so much power to these Games, and really focused towards the flame going out. That's our emotion."
Final rehearsals for the closing ceremony took place in east London on Friday and included the British band fronted by Chris Martin, who is married to the Hollywood actress Gwyneth Paltrow, Gavin added.
The executive producer for all four Olympic and Paralympic opening and closing ceremonies, Stephen Daldry, said Coldplay had been paid the 1 ($1.6, 1.26 euro) contractual fee to perform, "VAT (sales tax) included".
One sequence would include injured British former armed forces personnel and the Help for Heroes charity, that helps to rehabilitate wounded veterans from battlefield injuries in places like Afghanistan and Iraq, he added.
Their contribution will be "devastatingly emotional", he added.
Wounded former military personnel have been a key feature of the Paralympic Games. On Friday, ex-US Navy lieutenant Bradley Snyder won swimming gold on the first anniversary of the explosion in Afghanistan that blinded him.
The hosts of the next Olympic and Paralympic Games, Rio de Janeiro, will have an eight-minute slot in the show, to give spectators -- and athletes -- an idea of what awaits them in Brazil.
"If a nation has a spirit, Brazil's spirit is one of joy," co-artistic director Daniela Thomas told a news conference on Friday.
"In eight minutes, we are going to try to be contagiously joyful. It is just a taster of what you will get in four years' time."
The segment will involve both non-disabled artists and those with a disability, including a routine involving blind ballet dancers and the Brazilian principals at the Royal Ballet in London, Thiago Soares and Roberta Marquez.
Swimmer Daniel Dias, who won five golds in London, and four-time Paralympic champion sprinter Adria dos Santos will also feature, she added.
Rio's organising committee have promised to "raise the bar even higher than London" when the Games go to South America for the first time.
The ceremony begins at 1930 GMT and will also be streamed live on the Internet, including on the site of the International Paralympic Committee, paralympic.org.