The Aqueduct allows a city to grow beyond population 6, up to 12.
The Hospital allows a city to grow beyond population 12.

Both of these buildings have fields that are checked ("on") in the editor.
So, is it correct to assume that if these fields are not checked that cities will never grow beyond population 6?

Or, is it that by not checking these fields, you allow cities to grow to what ever size it's tiles will support?

Does anyone know?

It's the second of the two possibilities you suggest. If you have no Aqueduct-type building in your mod, then cities will grow beyond size 6 without one. Similarly, if you have no Hospital-type building, cities will grow beyond size 12 without one.

So if you want (say) to allow no cities ever to grow beyond size 12, you need to ensure that your mod contains a Hospital-type building, but it can never be built (eg requires an unfindable resource).

Also, don't forget that you can change the limits for the kinds of cities - eg allow cities to grow only to 4 before requiring an Aqueduct and then to 20 before requiring a Hospital, or whatever.

As I suspected.
Thank you very much.

Also note that you don't have to have improvements with the flags Allows City Size Level 2 and Allows City Size Level 3. You could give Wonders those flags making it possible for a few cities to grow really big while the majority won't get past size 6 or 12. That works, I've just tested it. :D

Hey Azmorg, I'll test a game with Accelerated production and a working Aqueduct, and flagging one of the Great Wonders with Allows City Size Level 3. Then, without polluting supercities everywhere, we'll see if the game slows enough to make it into the 5th Century AD... :mischief:

Wolfhart! Thats priceless! I`ll try to implement it in the 40k mod! :)

Good info, Wolfhart! :goodjob:
I await your further analysis with baited breath. (Guess I need to brush my teeth). :crazyeye:

In the Twillight of Byzantium I made the only building that would allow size 3 a wonder and placed it in Constantinople, it works great:)