One might take the Kowloon Walled City as an example of organic human architecture.

It would indeed be interesting to see where architecture ends up when given a ride on a genetic algorithm, although the parameters will need to be very, very detailed, and might be compiled from inputs such as "people always get lost at these 5 intersections", "this corner smells bad on hot days", and "raw sewage comes out of my tap when more than 6 people shower at the same time".