Functional communities must physically evolve to exist –a simple fact often ignored by urban planners and architects and which applies just as much in space as on Earth. A town or a city is not so much a specific built structure as it is an emergent phenomenon, created by a convergence of individual interests upon a single logistically advantageous location, its form a physical manifestation of environmental constraints and a collective social situation that can –and almost always does– change, sometimes slowly, sometimes with alarming speed.