“Houses of the Holy” was cut from its own album.

The song “Houses of the Holy” was recorded during the Houses of the Holy sessions in 1972, but it didn’t make the cut. The band felt it didn’t fit the flow of that album. So they shelved it and two years later dropped it onto Physical Graffiti as a bonus track for fans who’d wonder where the title went.

Other Physical Graffiti tracks like “The Rover,” “Night Flight,” and “Down by the Seaside” were also leftovers from earlier sessions. But the title track is the most famous example of a song getting bumped because it just didn’t feel right at the time. Zeppelin treated albums as coherent wholes, not just hit collections.

So if you ever wondered why Physical Graffiti feels like a double album of outtakes and new stuff — it pretty much is. And it’s brilliant.