Yes may lie at the heart of the Progressive Rock movement, with their complex arrangements and symphonic sound. They are probably the core Progressive band that has the most songs in radio rotation today. But less well-known, and far less frequently heard, is the act that is the bedrock of Prog’s other half, the experimental and avante-garde.

1969’s In the Court of the Crimson King was deeply influential to the Prog movement, and its effects can still be felt in contemporary successors like Muse, the Flower Kings and Porcupine Tree. It was King Crimson’s first album, and it’s probably their most accessible. The title track, which you’ll see below, is still heard occasionally on the abomination that is corporate radio, much less frequently than the band’s lone other entry on Classic Rock stations, ’21st Century Schizoid Man’, which has seen numerous covers.

King Crimson is not representative of the experimental side of Progressive Rock; in five decades, it has defined it, and with its fusion of rock, symphonic sound and improvisation, set the stage for other avante-garde (and even weirder, in some cases,) acts.