Led Zeppelin's thrillingly outsized soundtrack for Song Remains the Same didn't suffer from the film's momentum-stealing dream sequences, but the album still had its own problems. Namely, the head-scratching exclusion of some key cuts from the movie, and the lingering sense that Led Zeppelin hadn't lived up to the moment.

Ironically, The Song Remains the Same was recorded over three nights in July 1973 at Madison Square Garden as Zeppelin was peaking commercially. And, in time, it's become something of a representational touchstone for an era of rock excess unseen before or since – a testament to sheer spectacle. But these New York City shows represented the last on a lengthy tour, and Zeppelin seems worse for the wear at times.

As a result, Jimmy Page always saw the project as more average than career defining. "Well, it's not a terribly good night and it's not terribly bad," he memorably told Creem in 1977. "Certainly not a magic one, but not ... tragic."

Unfortunately, by the time The Song Remains the Same arrived on store shelves three years later on Oct. 22, 1976, things had actually turned quite tragic. In 1975, Robert Plant's car plunged off a cliff on the Greek island of Rhodes, leaving both the singer and his wife badly injured. For about a year and a half, it was unclear whether Plant would ever walk again – leaving him to do sessions work for a new studio effort while in a wheelchair.

With Led Zeppelin's time off the road now stretching toward two years, they released The Song Remains the Same to fill the void, just seven months after 1976's Presence. The film was a box office hit, reportedly grossing some $10 million in 1977, and its associated soundtrack stood as Zeppelin's lone live document for years. Yet critics – including members of the band – weren't always very kind.

"It was not a great film," Page admitted in 1976, "but there's no point in making excuses. It's just a reasonably honest statement of where we were at that particular time." Plant went even further, calling The Song Remains the Same "a load of bollocks."

Listen to Led Zeppelin Perform 'No Quarter'

The reasons, back then, were many. Even leaving aside the movie's head-scratching non-musical interludes, Led Zeppelin were being widely accused of yielding to bloated ego. "Dazed and Confused" yawned to a half hour in length, while four other tracks were more than 10 minutes long. "On 'Song Remains the Same,'" Page once told Cameron Crowe, "you can hear the urgency and not much else."

He later pointed to a pre-show backstage robbery as one notable distraction. Others criticized the post-production editing process for both the film and album. After all, the original soundtrack included "Celebration Day," but not "Black Dog" – while, in the film, the opposite was true. "Since I've Been Loving You" and "Bron-Yr-Aur" were also left off the vinyl edition, while others were featured using different takes.

Fast forward to 2007 and an expanded reissue – bolstered with new liner notes by Crowe – added back six songs. By then, however, it seemed the public's idea of this as a failed project was set in stone. Certainly, Page spent years ruminating on it. After all, but for an extended touring lull, things might have gone another way for Led Zeppelin. He's said he felt boxed in by looming deadlines, the limitations of making a companion film and the need for product. As far back as the late '70s, Page had plans to produce a more linear concert recording – though that didn't finally take shape until 2003's How the West Was Won.

Still, there was no denying the eye-popping grandeur of The Song Remains the Same at its bow-fiddling best, as Zeppelin took their music to its absolute zenith. For all of its warts, there may not be a better document of the larger-than-life arena-rock era. They found new depths in moments like "No Quarter," too.

"It was a shame," Page told Trouser Press in 1977. "After Robert's accident, we were forced to tie it all up. We'd done work with it already and it had to come out. It was recorded across three nights, but in fact the music for the footage mainly came from the first night. It was the best vocal performance ... but they just didn't have complete footage. So, we had to come up with the fantasy sequences to fill it up. Had we been a band that's the same every night, it would have been very easy for them to link one night's performance with another. As far as live albums go, most groups will record over half a dozen nights and take the best of that, but as it was a visual, we couldn't do that."

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