A visit to an Elton John show at London's O2 Arena cemented Led Zeppelin's one-off reunion in 2007 - because bandmates John Paul Jones, Jimmy Page and Robert Plant were so impressed by the spectacle.
The trio was considering a one-off get together to honour late music mogul Ahmet Ertegun but feared there wasn't a suitable venue to host the show.
Then promoter Harvey Goldsmith took them to see Sir Elton John at the O2.
David Campbell, president and CEO of AEG Europe, the company behind the venue - tells CelebrityAccess.com, "We were going through (the venue) with the band, and Mr. Page said, 'I bet it doesn't sound any good up there.' So, with all of them, as well as Harvey and myself, we took the elevator up to Level 4 to go to the very top of the building to have a listen.
"Someone held the elevator, and we were sort of standing there waiting for them to go. They just put their thumbs up, and sort of smiled at each other. That's when Harvey and I knew that this was going to be OK. Then, John Paul Jones started running up and down the stairs; and that was it."
But it wasn't just the sound that impressed the rockers.
Campbell adds, "It was Elton John's Vegas show that was playing in the arena at the time. It had a massive LED screen that is very similar to the one we have in Vegas, in Caesar's Palace in The Coliseum. The remark (from Led Zeppelin members) as we went back to get into the elevator to go down was, 'That screen, we have to get one just like that - but bigger.'"
But they still weren't sure about a reunion: "As we walk out to take them back to their cars, they are going, 'Harvey, there are lots of rumours around about us reforming, and getting back to together. You have to put a stop that. You have to get people to stop writing about it in the press.'
"Harvey says, 'What do you mean? The four of you just stood in a public arena together. What am I supposed to do?' So it was, 'OK, fair enough.'"
Led Zeppelin did reform for the magical one-off show but the band has since refused to come together again for a dream reunion tour.