This is all stuff that never appeared in the game, but I think that makes it all the more interesting. You're looking at the "what could have been" here, not what you already know, only slightly different! What actually was put into the game doesn't capture the imagination nearly as well as the things that don't actually exist, don't you think?
So Diablo: IncGamers have a post where they delve into the work of Christian Lorenz Scheurer, a man who created concept art for Diablo III early in its development. None of what he produced made it into the actual game–though they almost make it sound like it's possible we'll go into these locations at some point in the future. As an example of the type of art this features:
Heaven
You see a couple of his takes on the High Heaven below. Not totally different than the final game, but much darker in some ways. Clearly the floating islands of buildings and structures was a design idea going way back to the Blizzard North version of Diablo III, as many artworks as it shows up in.
Click through for 9 more pieces, showing a bunch of never-before-seen views of places like the Wizard homeland of Xiansai, Westmarch, plus some mystery areas; the Well of Souls (meant as a dungeon in Heaven?) and someplace called Sandencal, which looks a bit like Caldeum and a bit like Heaven. (It even gets an elusive Google-whack when searched for.)
All these images and hundreds of others are available in the Diablo Gallery in the Diablo 3 Environmental Artwork folder.
Nothin' like the heaven I'd think up, I'll tell you that much. If you'd like to look at the concepts in full, check out the full post here.
