This is not a story. This is, most likely, Math. If you're interested in the nitty-gritty details of building cities, then by all means, keep reading! If, however, you are only here to read stories and look and cool maps, you might want to give this a skip. Don't say I didn't warn you!
The Adventurer, Conqueror, King System has very straight-forward rules about empires, kingdoms, all the way down to itty-bitty villages. That said, it can get quite complicated quite quickly; I'm not entirely sure how someone could create an entire world with fully-populated urban areas without that being their full-time job. That said, I took some shortcuts. Short-ish, anyway.