From 1967, please enjoy first generation San Francisco band The Serpent Power and their 13 minute album-closing epic "Endless Tunnel."
Let's say that again...Serpent Power. "Endless Tunnel."
Jeebus, that's about as subtle as Whitesnake covering "Sugar Walls."
Seriously, this song is so hilariously portentous in a kind of sub-Doors way I've always had a sneaking affection for it; I seem to recall that the late great Allison Steele, a/k/a The Night Bird, used to play it all the time on WNEW-FM back in the day, thus occasioning much stoned 2:00 AM giggling at Casa Simels.
It is also worth noting that the blonde guitar player on the bottom left of the cover photo is clearly David Spade. What he was doing in San Francisco during the Summer of Love, I have no idea.