Virtually everyone who knows anything about rock will agree that the FIRST totally prog LP was King Crimson's "Court of Crimson King". Released Oct 10 '69 .
Wot are contenders for the second-most prog rock lp?
(Note that I stipulate prog ROCK. I am not necessarily interested in the word "progressive" in the sense of music that advances / is an improvement upon. It has to be in the rock oeuvre , or - since we are dealing with 60's - poprock. We are not talking things like Miles Davis or Dylan going electric.)