Truth be told, heavy metal and prog rock have been intertwined since both genres were born. My friend Frank, who is a few years older than me, remembers confusing Black Sabbath's "Iron Man" with King Crimson's "21st Century Schizoid Man" in 1970, when both songs were new. (Interestingly, both were also referenced on Kanye West's My Beautiful Dark Twisted Fantasy 40 years later -- coincidence?) And as different as Crimson and Sabbath might sound to us today, what's still clear is that both moved rock away from blues-based rhythms and toward more European concert-hall structures: Sabbath by way of horror-movie soundtracks, maybe -- but nonetheless. Of course, compared to most contemporary metal, Sabbath might as well be Muddy Waters.
That's partly because, around the turn of the '80s, bands like Iron Maiden subtracted even more of early metal's R&B groove, and later most thrash bands and their descendants finished the job. In the '70s, being that devoid of African American influence is something only bands like Yes and E.L.P. would've copped to. So Maiden, in fact -- from Bruce Dickinson's Shakespearean-actor declamations about ancient mariners and flights of Icarus on down -- might just as well be considered a really loud prog band, and maybe would've been had they emerged a few years earlier.
And once they (along with Rush and any number of other '70s brainiacs) set metal on that pomp-and-circumstantial path, impenetrable concept albums, rock operas, half-hour multipart epics with symphonic midsections and countless other subspecies of pretentious bombast were inevitable. Starting at least with Queensryche in the late '80s, progressive metal has occupied its own ornate mansion on the genre's map -- albeit a mansion that metal's myriad other substyles (from death to doom to power to nü) visit on occasion. Here's a rundown of some notable albums.