How big can vanilla cities get?

[justaplayer]

How big could a vanilla city get by population? 1000000? 10000000? or even up to the 64bit integer limit?

[Baldy's Boss]

I suppose you could multiply the maximum population of a building by the maximum area a local authority can cover...and allow for streets.

[Erato]

Alternatively, go in the scenario editor, place a town in the centre and spam "expand". Remove all the buildings from the city centre every once in a while to replace them with taller buildings, and repeat until the map is filled.

[Eddi]

the highest i've seen during gameplay was something around 3 million, but i don't remember if that was with NewGRFs

[_dp_]

About 2.5 mil is the max city possible to grow naturally in vanilla temperate climate.