ground zero

a thing or place that is of greatest importance to an activity or interest <a city that was once ground zero for the insurance industry> Synonyms axis, base, capital, central, core, cynosure, epicenter, eye, focus, center, heart, hub, locus, mecca, navel, nerve center, nexus, nucleus, omphalos, seatRelated Words headquarters; happy hunting ground, hive, hotbed, hot spot, playground, playland; kernel, nub, pith; deep, thick; essence, quintessence, soul; attraction, lodestone (also loadstone), magnet, polestar