In 1973 in Tampa, Florida, they played to more than 56,000 fans, breaking the Beatles' Shea Stadium record.
As one newscaster put it, "It really was the biggest crowd ever assembled for a single performance in one place in the entire history of the world!"
"I guess we were on a roll," Page said.
"By all accounts, [you] lived a pretty wild life while you were doing it as well," said Mason.
"I don't know!" Page replied.
Which brings us back to that quote from Joe Perry, the guitarist with Aerosmith: "Mad, bad and dangerous to know."
"And also 'to hear,'" Page smiled.
For more than a decade Led Zep were the dark gods of rock. But in 1980, when drummer John Bonham died after consuming 40 shots of vodka in 24 hours, it all ended unexpectedly.
"That must have been an incredibly difficult decision," said Mason.
"No, it was an easy decision," said Jones. "It was an incredibly difficult time. But I just couldn't imagine the band without him."
The band members went their separate ways.
"I've never felt so out of place and vulnerable and out of time and all that stuff," said Plant. "It was nerve-wracking, but that's what nerves are for."
Led Zeppelin would reunite publicly only twice before 2007, and with disappointing results. So when the concert to honor Ahmet Ertegun, the late head of Atlantic Records, was planned, Plant worried about recapturing Led Zeppelin's old magic:
"Did you have to work pretty hard to put yourself back there?" Mason asked.
"I knew I couldn't go back there. But I had to be comfortable with where I met it," said Plant.
"And where was that?"
"Just left of extreme fear, trepidation," he laughed. "Because it's a tall order, you know? The thing is, everything that's magnificent, whatever it might be - a great moment in sport, a great moment in literature - can people actually ever go back and touch that again? You just know that once upon a time you could kick ass together, and that's about it."
But as "Celebration Day," the new film of the concert, shows, for that one night, with Jason Bonham taking his father's place on drums, Led Zeppelin would soar again.
The band's performance raised hopes of a reunion tour. But at the premiere of "Celebration Day" and the DVD release press conference last month, the question ("Why is it so hard to get back together again?") was met with silence.
They didn't like it when we brought it up, either.
"I'm sure you've been offered a great deal of money ..." Mason said.
"Are you still on about it now?" Plant said. "Oh, what a shame, he was doing so well."
Away from the band, Jimmy Page was more receptive. "I've been open to it, but I think it's unlikely. I'm just looking at the history of it."
"Do think that was your last show?" Mason asked.
"It's likely, yeah. I think so," Jones said, then added laughing, "But I've said it before."
But if this was Led Zeppelin's last set, they went out with thunder and awe.
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