Encompassing heavy metal, folk, pure rock & roll, and blues, Led Zeppelin's untitled fourth album is a monolithic record, defining not only Led Zeppelin but the sound and style of '70s hard rock. Expanding on the breakthroughs of III, Zeppelin fuse their majestic hard rock with a mystical, rural English folk that gives the record epic scope. Even at its most basic - the muscular, traditionalist "Rock and Roll" - the album has a grand sense of drama, which is deepened by Robert Plant's burgeoning obsession with mythology and mysticism. These obsessions come to a head on the eerie folk ballad "The Battle of Evermore," a mandolin-driven song with haunting vocals from Sandy Denny, and on the epic "Stairway to Heaven," which encapsulates the entire album in one song.
