Submitted by Arne, who says:

It suddenly appeared to me that the Berlin S-Bahn system had the form of Da Vinci’s Man of Vitruvius: a circle (Ringbahn), two arms (Stadtbahn) and a head + legs (Nord-Südtunnel and the southern branches at Yorckstrasse), with Friedrichstrasse as the heart of the network. So I made a map. What do you think?

Transit Maps says:

Well, that’s certainly a creative and unusual way to interpret the Ringbahn! Of course, it’s a diagrammatic representation, so things can be tweaked to suit the designer’s vision – lining up Schöneberg with the Vitruvian Man’s left foot; raising the Stadtbahn’s horizontal axis up to mimic the arms, etc. The real Ringbahn is nowhere near so perfectly neat, taking a far more convoluted path through Berlin’s outer suburbs. According to Wikipedia, the distinctive shape formed by the Ringbahn earns it the the nickname “Hundekopf” (dog’s head)… which I can just about imagine if I squint long enough at the real map.

Still, full marks for creativity and the skill to turn that idea into something convincing!