Columbus, OH
You may notice the "V" in most of these pictures. All these were done by a person who goes by the name "Vinchen." I have received several emails from people claiming to know him, but they are never specific about him. These are all done in very high-traffic areas, where I would think it would be hard to paint something this detailed without being seen.
I found the graffiti pictured below under a bridge on Route 33. You can see it as you drive over.