In March of '73, Robert Plant and Jimmy Page held an acoustic performance in Hamburg, Germany, just ahead of the release of Zeppelin's fifth album, Houses of the Holy. The album showed the band expanding their sonic universe even more, including incorporating a heavier dose of synthesizers and some serious Mellotron love. Ironically, the song "Houses of the Holy," which was recorded during the Houses of the Holy sessions, didn't actually make it to vinyl until Zeppelin's '75 album Physical Graffiti.

Controversy hounded Houses of the Holy because of the album's cover, which depicted nude children, photographed from behind, making their way up the Giant's Causeway in County Antrim, Northern Ireland. The album was banned in many places, including Spain and all over America's Bible Belt. Of course, what they say about publicity – bad or good – held true, and the album shot to the top of the charts. The resulting tour was colossal. Zeppelin packed 56,800 fans in Tampa Stadium, shattering the previous record set by The Beatles during their 1965 Shea Stadium scream-fest, and they easily sold out Madison Square Garden for three consecutive nights, and event that was filmed and eventually released as the motion picture The Song Remains the Same.