When Terry Riley brought 10 musicians into a New York City studio in 1968 to record an album-length version of his composition In C, he couldn't have known how profoundly he was about to affect the course of contemporary music, both popular and experimental. Minimalist music was around before In C, but this was the album that really put that approach on the map. Influenced by everything from Indian music to John Cage's chance-oriented pieces, this modal marvel is a cyclical composition consisting of short, repetitive phrases that each player chooses spontaneously from the score, creating a hypnotic interlocking of lines based around a central idea. Piano, vibes, marimba, woodwinds, horns, and viola meld together in a slowly shifting, pointillist landscape. When the album was released, composers like Steve Reich and Philip Glass were following minimalist paths as well, but they were still pretty far underground. In C not only broke through to avant-garde ears, it proved profoundly influential to adventurous rock and jazz artists.