Led Zeppelin: Heavy Blues

It's a rare Led Zeppelin song that isn't helped along by the blues. Whether it's the band's amped-up, hip-shaking take on Willie Dixon's “I Can't Quit You Baby” or the leviathan drums and propulsive feel of “When the Levee Breaks,” underneath Jimmy Page's electric guitar wig-outs and Robert Plant's rib-rattling wails you can hear the Mississippi Delta.