The First Concept Album

[jaycee]

This is something I've thought about every so often - what should be considered the first real concept album? I.e. not something loosely like a concept album, or a kind of gimicky concept (e.g. Colorful Ventures by The Ventures), but a complete, fully unified concept.
I would say Days Of Future Passed by the Moody Blues (have a glance here, http://en.wikipedia.org/wiki/Days_of_Future_Passed, and buy the 2008 remaster if you haven't already!! ) - each song is associated with a time of day, tracing an "everyman's day" from dawn to the night.
Some might try to argue for Sgt. Pepper's by The Beatles, although I think it's harder to justify...
Others may argue for even earlier albums like Dust Bowl Ballads by Woody Guthrie, if they've heard them!
So, let's hear everyone's thoughts on the matter! Fire away!