Help! Looking for environment images :)

Hi chaps, really hope you can help. Im a primary school teacher and am starting a new education project which will be a physical adventure in school halls. The children will work in teams and travel around the desolated Earth looking for clues to save the planet. What I need is - environment images that people have already made that they wouldn't mind me licensing me to use. I would blow up the images to 2m and use them as scenery to set the zones. Id be ideally looking for deserted, empty, broken, mysterious or creepy scenes - anything really. It won't make anyone rich but could give it a little in appreciation, would plug on my website / twitter etc and would be a new audience for their portfolio.  If can't help then pls feel free to direct me where I may have some success! thanks guys!!