From the very beginning, part of what made Led Zeppelin so unique was the band's curiosity with traditional genre forms. They've been known, throughout the years, as musical plagiarists--and there's some truth to that claim, judging by their slew of copyright lawsuits from blues legends like Willie Dixon. But even when they were borrowing from folk and blues songs without permission, Zeppelin were unafraid to explore, refine, and update the music that came before them, such as on 'In My Time of Dying,' which is No. 6 on our list of the Top 50 Led Zeppelin Songs.

The 11-minute behemoth and centerpiece of the band's 1975 double-album, 'Physical Graffiti,' 'In My Time of Dying' is the band's most vibrant attempt at updating a traditional tune--in this case, the routinely covered gospel standard 'Jesus Make Up My Dying Bed.' The track is built around Jimmy Page's lumbering, open-tuned slide-guitar riff, with Robert Plant channeling his inner gospel belter over the rhythm section's galloping grooves.

Though it's the longest single track in the entire Zeppelin cannon, it's never tedious. Plant's bone-chilling moans set a bleak mood, as the singer ponders his own death, but the band builds and releases tension with expert precision, with John Bonham firing sparks off his hi-hat while John Paul Jones anchors the mix with his thick fretless bass.

For such a talented group of players, Led Zeppelin rarely stretched out into 'jamming' in the studio--their songs were usually far too disciplined. But 'In My Time of Dying' is quite possibly their most spontaneous-sounding track, and the lengthy run-time lets the players cut loose into a mighty torrent of death-bed ruckus.