For rockers of a certain age, Montreux will always be best known for its rich musical history — including the roaring casino fire that inspired the English rock band Deep Purple's classic "Smoke on the Water." The story goes that on Dec. 4, 1971, Frank Zappa and the Mothers of Invention were playing a gig at the Montreux casino. The band was nearly 90 minutes into the show, cranking through "King Kong," when someone in the crowd fired a flare gun at the wooden roof, which instantly caught fire. Deep Purple was in Montreux with a sound truck rented from the Rolling Stones to lay down some tracks. They were forced out of their rooms by the fire, but memories of the smoke billowing out across Lac Leman, or Lake Geneva, gave them a song title. Before long, Ritchie Blackmore's classic guitar riff was being copied, it seemed, by every cover band and guitar-playing teenager. "Smoke on the Water" reached number 4 on the Billboard pop singles chart in 1973, and in 2004 was included in Rolling Stone magazine's "The 500 Greatest Songs of All Time."