This concept art for a medieval-styled seaside trading port has a really excellent mood, especially with the layering.
Nagai Hideyuki uses two sketchbooks to create 3D illusions. I was thinking this may be possible to do on the street/buildings with chalk, but in order to view it correctly everyone would have to be the same height, so that probably wouldn't work.
7 drawings show that animals never don't want to stay in lines! There's too much cuteness to handle!