I have to admit, sometimes when I'm depressed my mind is like the castle in the short story The Outsider by H.P. Lovecraft.
My mind would pretty much be some sort of psychedelia, Pepperland-esque place. Full of music and just plain weirdness.
I can see it, Gi. Okay, I suppose I can post mine. Mine is mostly this thick, thick forest with a bazillion trees and vines and stuff. There aren't really any paths going in or out, you just kind have to push your way through everything. And scattered around everywhere are all of these random objects. At the very, very center of it is a clearing with lots of bright green grass and a single tree with a rope swing on it. That's all.