I've called this post 'Right Angles in Perspective'. It took some thinking about. It's another webfind that I remember nothing else about. (These things get saved to the camera roll on my iPod and that's that.)
Needless to say, it appeals to my fondness for right-angles, rectangles etc although, if you look closely, there are no right angles per se in the whole image!
It is not difficult to guess how this 'impossible' (Escher-like) image was staged but it is impossible (I find) to see the overlap. (I have a suspicion but I'm just not sure.)