Update: Greg sez, "The site with the building carved into an ATAT is a photoshop hoax. Check the two pics side by side on the site and note the white van, the guy in the red shirt, and the motorcycle. It's the same picture only one has been artfully photoshopped!" I'm not sure; the site's confusing. I think this may be an architect's rendering of the plan, not a hoax.
Update 2: Sioen sez, "this was a submission to an art/design competition for the Shrinking Cities concept."