As Nirvana’s Nevermind sessions were about to get under way, neither the band nor producer Butch Vig knew just what they had on their hands. “The week before I flew to L.A. [to produce Nevermind], Kurt sent a cassette, which was done on a boombox,” said Vig. “It was really terrible sounding. You could barely make out anything. But I could hear the start to ‘Smells Like Teen Spirit,’ and I knew it was amazing.” Click through to read about the making of Nevermind.