Eco-Compact Metropolis

Main city of a Region or State as is from the ancient Greek language meter = mother and polis=city, that is "mother-city" in relation to other derived urban settlements by foundation or administration. It is a prominent city in terms of public function, but can be also any bigger urban settlement, indipendently from its anthropogeographic cathegory, with a population higher than a specific level, for example, a million.
Metropolis are made of a polycentric structure of cities, neighborhoods, district, faubourgs and villages.