Metropole

The metropole, from the Greek Metropolis 'mother city' (polis being a city state, hence also used for any colonizing 'mother country'; in ecclesiastical languages an archbishopric having precedence over the suffragans in its ecclesiastical province) was the name given to the British metropolitan center of the British Empire, i.e. the United Kingdom itself. This was even extended, such that London became the metropole of the British Empire, insofar as its politicians and businessmen determined the economic, diplomatic, and military character of the rest of the Empire. By contrast, the periphery was the rest of the Empire, outside the British Isles themselves.
See more at Wikipedia.org...

n. metropolis, mother city, capital city; main city, important city

n. metropolis

n. city, metropolis

n. wen