version 1 , polite. there are a bird perch, a bird nest, and a bird's egg on the ground of Beijing.
version 2 , sharp architect's humor. A guy is about to poop (CCTV building, anthropomorphic. Sorry Rem). He is looking for the toilet, but can't find it (national stadium, sorry Herzog.. but that's the shape). So he does it on the street (National theatre).