For this week's episode, we climb aboard the rock-and-roll mothership that is Led Zeppelin and their mysteriously untitled fourth album. What more could possibly be said about this ubiquitous classic-rock staple? This week's guest Ralph Cavallaro describes how the record/band went from seminal hard rock touchstone in his youth to bloated, uncool anachronism in his college years to one of his all-time favorites today. Along the way we dig into the sonic artistry and groundbreaking recording techniques that make this a stone cold classic.

Songs featured in this episode: Anymore - Quit; The Song Remains The Same - Led Zeppelin; Terrible Lie - Nine Inch Nails; Icky Thump - The White Stripes; Rocks Off - The Rolling Stones; Detroit Rock City - KISS; The Pretender - Foo Fighters; Black Dog - Led Zeppelin; Oh Well - Fleetwood Mac; Cinnamon Girl - Neil Young; Keep a Knockin' - Little Richard; Rock and Roll - Led Zeppelin; Book Of Love - The Monotones; Rock and Roll (Live) - Foo Fighters; The Battle of Evermore, Stairway To Heaven, Misty Mountain Hop, Four Sticks, Going To California - Led Zeppelin; California - Joni Mitchell; When The Levee Breaks - Memphis Minnie; When The Levee Breaks - Led Zeppelin; Time - Pink Floyd; Whole Lotta Love (Live) - Prince; Rock and Roll (Live) - Led Zeppelin