By 1973, Led Zeppelin ruled the world. On Houses of the Holy, their 5th album, they rose to the challenge of breaking new ground. The continual move away from heavy metal got the album mixed reviews. But it topped the charts and sold 11 million in the US alone.

The mellotron-driven 7 minute The Rain Song was inspired by George Harrison’s complaint that Zeppelin didn’t do ballads; the opening two notes borrowed from Something. While Page used guitar riffs as architectural motifs on The Song Remains the Same, No Quarter was a John Paul Jones showcase for a tale of a battle in a snowstorm. They tried reggae (D’yer Mak’er), funk (The Crunge) and doo-wop (The Ocean - a tribute to their fans). It came wrapped around the gorgeous cover of children at the Giant’s Causeway, Northern Ireland, inspired by Arthur C. Clarke’s novel Childhood’s End.

Led Zeppelin’s “Whole Lotta Love” is credited with taking the blues into the space age.

Last year, at the closing ceremony of the Beijing Olympics during the handover to London as the host of the 2012 games, the song chosen to represent the moment was Led Zeppelin’s Whole Lotta Love. A white-haired Jimmy Page performed it with singer Leona Lewis. Naturally, with a global audience of 2 billion watching, organisers moved to change the lyrics from “every inch of my love” to “every bit of my love.” Nevertheless, it was still a thrilling moment.

Whole Lotta Love — especially THAT RIFF — has that impact on people. It was used as the theme song for the BBC’s Top of The Pops — although ironically the band never appeared on the show because their manager Peter Grant refused to let them do TV. In 2004, it ranked #75 on Rolling Stone magazine’s list of the 500 Greatest Songs of All Time. A year later Q placed it at #3 in its list of the 100 Greatest Guitar Tracks. In 2009 it was named the third greatest hard rock song of all time by VH1. Interesting versions are by Tina Turner, Alexis Korner and Jack Johnson.

Robert Plant, when asked by Spin magazine what he regarded as Page’s “coolest, heaviest, most metal” riff, had a couple of choices. But he finally opted for Whole Lotta Love — “it’s quite a sexy track.”

“It was a very good period, 1968 – there was a good feeling in the air,” Mick Jagger recalled. “It was a very creative period for everyone.”

When the Rolling Stones got together at London’s Olympic Studios in March that year to start work on Beggars Banquet it marked the beginning of a five year purple patch unmatched by any other band before or after.