Rock Milestones Led Zeppelins IV zeroes in on Zeppelins fourth LP an untitled effort that shot to the top of the charts upon release circa November 8 1971 and singlehandedly shaped the landscape of hard rock over the ensuing decade Rock Milestones Led Zeppelins IV goes behind the scenes to investigate why and how this album became a decadeslong phenomenon and the inestimable impact it made on American music and pop culture in particular