Fleetwood Mac is by no means forgotten, but their original line-up before the additions of Stevie Nicks, Lindsey Buckingham, Bob Welch and Christie McVie is definitely obscure. The closest thing they had to a hit in the 1960s is this long song in two very distinct parts, Oh Well, written and sung by Peter Green. It starts with one of the greatest guitar hooks in rock history, breaking into a hard driving instrumental section that could easily be identified as early heavy metal. Then it breaks into a completely different melody on acoustic guitar and recorders, little wooden flutes famous for going out of tune after about a month of use due to saliva and heat warping the little bastards. I know, I used to play the recorder.
Then the symphonic section with flamenco guitar begins, which could be fairly considered a distinct third part.
I fucking loved this song in high school, when it was only FM radio that would play it. As a single, it had to be broken into Part 1 and Part 2, but FM radio would play whole thing straight through. I would lie in bed in the morning hoping the DJ would play it before I had to go to school. The only thing I can compare it to when I was a kid was the Traffic album John Barleycorn Must Die.
Peter Green had schizophrenia and the drugs didn't help. He has been in and out mental institutions much of his life. Still, he wrote some great songs and other musicians could see how damned good he was. His other great contribution to rock history is writing Black Magic Woman, turned into a hit by Santana. Oh Well has been covered by a whole passel of musicians, including Tom Petty & the Heartbreakers, Joe Jackson, Ratt, and The Black Crowes with guest guitarist Jimmy Page. Musicians loved the hell out of this, but it's public reception is tiny compared to the album Rumors took off.
Here's Fleetwood Mac, led by the musical genius Peter Green, playing the original version of is composition Oh Well.