Led Zeppelin kicked off their latest U.S. tour on May 4, 1973, beginning a jaunt that became legendary thanks to The Song Remains the Same.

They'd become the biggest band in the land by the spring of 1973. The immediate success of Led Zeppelin's new album, Houses of the Holy, only made that case stronger. Released just a couple of weeks prior to the tour, the LP was flying off store shelves. Led Zeppelin had just hit the U.S. the year before, but demand was at an all-time high.

The tour began at the Fulton County Stadium in Atlanta with a record crowd of around 50,000. This was topped the following night in Tampa, where Led Zeppelin drew more than 55,000 fans, grossing $309,000. That broke the record for a one-day event for single act, previously held by the Beatles for their 1965 Shea Stadium show.

Fans worldwide got to see the concerts for themselves when the three Madison Square Garden gigs that ended the tour in July were recorded for what would become The Song Remains the Same movie and LP. "The kind of speed we were moving at, the creative juices in the air, the whole thing was just an absolute mixture of adrenaline, chemical, euphoria, and there were no brakes," said Robert Plant in the liner notes to a subsequent reissue of The Song Remains the Same.

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Living the high life of '70s rock stars, Led Zeppelin even had their own private jet for the tour. A United Airlines Boeing 720B passenger jet, called the Starship and emblazoned with the band's logo, got them from gig to gig. But the tour wasn't without its problems. As documented in the film, Led Zeppelin had money (more than $200,000) stolen from a safe in the hotel they were staying at while in New York.

"Quite honestly, I don’t know why we’ve had such phenomenal success," Jimmy Page told the Los Angeles Times in 1973. “Perhaps you could relate it to street music and the fact that people feel more of an affinity to Zep’s music because it’s not constantly hammered down their throats from every direction.

"All I can say is that whenever we've gone on stage or into the studio, we've always done our best," Page added. "We've never really been involved in the media. We've never done a TV program, and air play, of course, is limited because of the fact that we don’t record singles."

The tour would end up as the largest grossing tour in rock history – for the time being, anyway – by grossing $4 million for 36 dates. “We can’t allow ourselves the luxury of becoming fascinated with our own popularity,” Page argued. “The way I look at it, if the Beatles were to get back together, they’d forget all about us again.”

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