Released in November 1971, the band's fourth album - which is officially untitled but is generally referred to as "Led Zeppelin IV" - features anthems such as "Stairway To Heaven", "Rock And Roll", "Black Dog" and "When The Levee Breaks". The album was inducted into the Grammy Hall Of Fame in 1999 and has been certified 23x platinum by the RIAA.

Released in March of 1973, "Houses Of The Holy" features "The Song Remains The Same" and "No Quarter" while showcasing the continuing evolution of the band's signature sound with the reggae-tinged "D'yer Mak'er" and the funk jam "The Crunge". The album has been certified diamond by the RIAA for sales of over 11 million copies.