King Crimson, In The Court Of The Crimson King (1969)
Look, I grew up in the 70s and 80s, when everyone had to go through a progressive rock phase. (Or at least every guy; I still don't know many women who have much tolerance for prog. My wife took me to see a Gabriel-era Genesis tribute band for my birthday last year, and I think she was the only woman in the theater. And yes, she hated it. Every. Fucking. Minute.)
In eighth grade, after a few years of AM radio top 40 obsession, I discovered classic rock (courtesy of a copy of Who's Next in the junior high library) and spent the next few years going down that rabbit hole, trying to master decades of rock history as quickly as my small allowance and the public library's record collection would permit.
It was Genesis that first got me into prog, or art rock, or whatever you want to call it. Duke and Abacab were all over the radio (and yes, I liked 'em, still do), and a friend told me I should check out their older material, back when Peter Gabriel fronted the band and Phil Collins was just the drummer. So I did, and I loved it. Like, deeply loved it. Nursery Cryme, Selling England, Lamb Lies Down, Foxtrot, Trespass -- those albums were revelatory, pushing the boundaries of classic rock, telling stories, extending rock's musical conventions. If you're a somewhat solitary, nerdy teen, locked away in your room spinning vinyl, this stuff was heaven-sent.
And that led me to King Crimson, which I'd read about as being somewhat comparable. This was before their early 80s Adrian Belew-era revival, when they were still defunct and pretty much absent from current rock culture; they were never played on the radio, none of my friends had heard of them, even the library didn't have any albums to check out. So based simply on a review of their debut album in the Rolling Stone Record Guide, and that crazy cover illustration, I decided to lay out a few bucks at a used record store and take a chance.
And this album blew me away. The opening track ("21st Century Schizoid Man") was a frenetic blast of hard rock and free jazz, completely unexpected, not something I would typically like, but it was so damn different that it quickly won me over. The rest of the album moved into more comfortable territory, mid-tempo balladry and weird jams and extended suites and all the bombastic overkill that made the progressive genre that grew in its wake such a love-it-or-leave-it proposition. It was gorgeous, entrancing; "Epitaph" and the title track were weirdly engaging, "Moonchild" and "I Talk To The Wind" tranquil and lovely.
I ended up picking up pretty much all the Crimson I could get my hands on after that, some of which I liked quite a bit, though nothing had quite the same inimitable magic as the first one (partially due to the absence of vocalist Greg Lake, who left shortly after the first album to form ELP).
From Crimson and Genesis, I went on to check out all manner of prog, from ELP to Jethro Tull to Yes and so on; none of which was as good, and a fair amount of which I truly hated. By the time I got to college and discovered R.E.M. and the Replacements and Husker Du and the Feelies and Sonic Youth and on and on and on, well, there was no room for prog, and of course my fellow college radio DJs looked down their collective nose at it. (Though oddly enough, the new incarnation of Crimson that was active at the time was fair game, maybe because singer/guitarist Adrian Belew had some cred from his time playing with Bowie and Talking Heads.)
Later, as an adult, I have found a comfortable middle ground and rediscovered a lot of these bands. Even the ones I didn't like back in high school, like Yes, I've learned to appreciate, if only because the remastered reissues of their albums SOUND so good that you can get past a lot of the excesses of the genre.
I couldn't find any good live footage of the band from this period, but here's a great live take on the title track from Genesis' Steve Hackett with some Crimson members: