Led Zeppelin released their fifth and most wide-ranging album, Houses of the Holy, on March 28, 1973.

After releasing their first four records in just under three years, Zeppelin were finally afforded a bit of breathing room with which to create Houses of the Holy. The record came out 16 months after their landmark (and technically untitled) Led Zeppelin IV. They responded by delivering some of their most complex, nuanced work ever, and by exploring new genres on tracks such as the reggae-influenced "D'yer Mak'er" and the funky James Brown-inspired "The Crunge."

"Although everyone was clamoring for another Led Zeppelin IV, it's very dangerous to try and duplicate yourself," guitarist Jimmy Page explains in the book Light & Shade: Conversations with Jimmy Page. "I won't name any names, but I'm sure you've heard bands that endlessly repeat themselves. After four or five albums, they just burn up. With us, you never knew what was coming next."

Highlights of the LP include the dynamic folk- and rock-mashing "Over the Hills and Far Away," the beautifully intricate ballad "The Rain Song" and the moody, keyboard-heavy John Paul Jones showcase "No Quarter." The album closes with a Robert Plant-penned love song to the band's fans, "The Ocean," which features one of the most famous count-ins of all-time courtesy of drummer John Bonham: "We've done four already but now we're steady..." 

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In order to keep things down to single-vinyl length, the band reportedly left future classic songs such as "The Rover," "Black Country Woman" and most famously, "Houses of the Holy" either unfinished or unreleased following the recording sessions.

When asked why the intended title track never made the album, Plant refused to lie to Get the Led Out author Danny Somach, instead declaring, "Being silly, isn't it? I mean, I could go into some great profound reasoning, but... I can't even remember why. I think we thought, 'Well, we'll hold onto that and we'll do something (with it).' It was just having a laugh."

Led Zeppelin underwent a massive tour in support of Houses of the Holy, which found the band glitzing up their stage show with lasers, mirror balls, pyrotechnics, fancier outfits and more. They broke just about every box office record known to mankind.

Even though Led Zeppelin traveled around the world in a swanky, custom-painted jumbo jet, the trek (and no doubt, the cumulative effect of their previous several years) left the band exhausted. It would be 18 months before they toured again, and nearly two years before they released their next record, 1975's double-album masterpiece Physical Graffiti.

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