I've been a fan of progressive metal since I was a kid, being into bands like Dream Theater, Fates Warning, Queensryche, and Cynic. I also dig some of the metal bands that sometimes have progressive tendencies, like Iron Maiden. Which makes me wonder; what is, in your opinion (and this is very subjective) the first prog metal album?
Also let us know if you have some progressive metal gems that we may not have heard: here's one song by Spiral Architect that for some reason never made it on to their only album (and in my opinion is their best song):
https://www.youtube.com/watch?v=1_wzwM5vBU4