Wait until you see China. There are multiple cities bigger than NYC or London that most people have never heard of.
https://en.wikipedia.org/wiki/List_of_cities_in_China_by_pop...
https://en.wikipedia.org/wiki/List_of_cities_in_China_by_pop...
There are still a lot of big cities and huge city centres but the Chinese meaning of city often includes the metropolitan area plus rural hinterland.
It doesn't get much denser than downtown Chinese cities, they have specialized in high-density mega-sized apartment buildings.
Even large US downtowns are dwarfed by the average Chinese city downtown flush with LED skyscrapers. They have way more people and manufacturing than other countries so it shouldn't be too surprising.