I'm reading the 4th book in Stephen King's Dark Tower series now, so I have a lot of imagery from the books in my head. Yesterday, at lunch, I started messing around in Photoshop on an image of Roland, the main character, with the Dark Tower in the background.
First, just a loose sketch to lay everything out:
By the end of lunch today I had quite a bit of the background laid in. I'm just working my way from back to front on this, trying to balance things as I go: