Cops Almost Stopped Rock's Most Iconic Riff From Being Recorded

Expensive steel-string acoustic guitar. Red cedar top, ebony fretboard, koa back and sides (not visible here). Camera: Canon 5D.

One of rock’s most famous guitar riffs was almost killed off before it was ever recorded, thanks to a police raid.
That’s according to Deep Purple guitarist Richie Blackmore, who says the band was recording “Smoke on the Water” at the Montreaux Casino pavilion theater when nearby residents called police to complain about the noise. “We did ‘Smoke on the Water’ there, and the riff I made up in the spur of the moment,” Blackmore says. “There was some hammering on the door. It was the local police, and they were trying to stop the whole thing because it was so loud.”
So the band locked the place up and let Blackmore quickly record his track for the song as police continued to pound on the door. Although the band had no intention of including the song on its album, it turned out they needed another song to fill out the album — so the band came up with lyrics for the track and added it at the last minute, Blackmore remembers. The song ended up reaching number four on the Billboard Hot 100.
What are some of rock’s other most iconic riffs?