Even though it grabs elements from other parts of Led Zeppelin's career -- including an 'Immigrant Song'-style crunch and an aggressive steamrolling thrust that would mark the 'Presence' sessions -- 'The Wanton Song,' No. 45 on our list of the Top 50 Led Zeppelin Songs, is firmly a product of 'Physical Graffiti.'

It all stems from the song's slippery groove -- part juicy funk, part hard-rock muscle -- which Jimmy Page feeds through the various studio tools that place the track in the mid '70s, when there wasn't any higher plateaus for the band to reach. Led Zeppelin were so infallible at this point that they could release a double album made up of old leftovers and experimental new cuts and still have it reach No. 1.

Besides that killer groove, 'The Wanton Song' features one of Robert Plant's raspiest, and most incomprehensible, vocals. Like so many of the group's songs, this one's all about sex with a pretty loose woman. Was it a tribute to their many groupies? Possibly. Either way, it burns with enough sexual energy to fuel a dozen or so five-star hotels.