Iron Butterfly

The heavily psychedelic Iron Butterfly was one of the first hard rock bands to receive extensive radio airplay, and their best-known song, the 17-minute epic "In-A-Gadda-Da-Vida," established that more extended compositions were viable entries in the radio marketplace, paving the way for progressive AOR. In-A-Gadda-Da-Vida -- the band's second album, following Heavy, released earlier in 1968 -- sold four million copies and spent over a year in the Top Ten. The follow-up, Ball (1969), went gold, but it also marked the beginning of the band's decline, and Iron Butterfly broke up in 1971.