On what would have been Princess Diana's 46th birthday, her sons, British princes William and Harry, have invited 62,000 people to celebrate.
The charity show William and Harry organized features such diverse acts as Rod Steward and Kanye West.
"I think she'd be slightly amazed that we actually managed to do this," Prince William said.
They said they were amazed with what they pulled off as they checked things out on stage.
"Actually seeing it in reality, it's suddenly bringing it to life," Prince William said.
William and Harry oversaw everything from the program, featuring their mother, to the music. Elton John was tapped to sing, "Candle in the Wind," which he sang as a tribute to Diana after her death.
Rosa Monckton, Diana's best friend will be there too. She said she thinks Elton will bring down the house.
"An extraordinary moment, it really will [be]," she said. "There was just something really extraordinary about that moment and the sudden realization she wasn't there any more."
The event will be devoted to celebrating the princess' life and the things she loved.
"I think it will be full of special moments," Monckton said. "And what I hope is that the overwhelming memory that people take away is one of joy celebrating the life of a truly extraordinary woman."
It's Diana's day, but all eyes will be on William and the rumored appearance of William's old flame Kate Middleton.
William diplomatically answered questions by saying he has a lot of friends coming.
Mostly, the day is for the princes to pay tribute to their mother.
"For us, we were so lucky to have her as our mother," Prince William said. "And there's not a day that goes past that we don't think about her and miss her influence because she was a massive example to both of us."