A friend of mine Always wanted to play Curse of the Crimson Throne, a Paizo adventure path set in Korvosa. This would be one of the most detailed cities in that setting. It has the classical wealthy/poor divide, values ostentation of power, wealth and knowledge and really likes predictability. It is a frontier city and one of the oldest at that and it was founded by the Kingdom of cheliax, a devilocracy based on italian renaissance.
I'm trying to fit it on the realms. It should face the sea, have barbarian tribes and orc raiders nearby and an evil empire wouldn't be bad.