Primate city
Some countries have one city (the primate city) which, in terms of its population size and functions, dominates all other urban places. A primate city is the leading city in its country or region, disproportionately larger than any others in the urban hierarchy.
A primate city is at least twice as large as the next largest city and more than twice as significant.
A primate city is number one in its country in most aspects, like politics, economy, media, culture and universities.