Montreux is in Switzerland. Deep Purple's 1972 international hit song from their Machine Head album, retells the true story of an incident on Dec. 4, 1971. While in Montreux to record an album using a mobile studio that belonged to the Rolling Stones at the Montreux Casino complex, Frank Zappa's band was playing a concert in the theater. This was going to be the last concert in the venue for the season. During the concert, someone in the audience fired a flare gun into the rattan covered ceiling starting a fire. Nobody suffered any major injuries, but the blaze destroyed the entire complex and Zappa's equipment -- some of which was going to be used by Deep Purple.

After some searching, Deep Purple was able to rent a nearly empty hotel in Montreux and recorded the album.

According to bass guitarist Roger Glover, the song's title refers to the smoke from the fire spreading across Lake Geneva. Glover admitted that the band initially thought the fire was a fireworks show and not a disaster. Other lyrics in the song refer to the incident including "some stupid with a flare gun." The lyric "Funky Claude running in and out" is referring to Claude Nobs, the director of the Montreux Jazz Festival, who helped some of the audience escape the fire.

The song features an opening guitar riff that was ranked No. 4 on Guitar Magazine's "Greatest Guitar Riffs" in 2004.

Montreux honored the song with a sculpture along the lake shore featuring the band's name and the riff in musical notes.

More Info: en.wikipedia.org