I was introduced to cities as "ecosystems" by the late Professor Forest Stearns (University of Wisconsin, Milwaukee) who was an early pioneer in the studies of the urban ecology in the 1970s. I still recall the various terms: "Urban ecosystem," "Urban zones" Urban corridors" Megacities" or "Megacities' complexes" and "Megalopolis" used by various discipline experts as they grappled with the complex of all the terrestrial habitats-the city. Cities have been humanity's habitat since ancient times and one can find references to the cities even in biblical writings and other ancient texts from...