After a slew of albums that built Led Zeppelin into the biggest rock band in the world, frenzied anticipation awaited 1975's Physical Graffiti. This double LP is a sprawling and adventurous effort, propelling the band away from its previous four-beat blues and roots sound, toward the scope of a progressive rock unit. It dabbles in Middle Eastern rhythms and folk stylings, as well as the band's signature heavy blues-rock riffs. Mastered under the direct supervision and approval of Jimmy Page.