GMs talk all the time about reskinning creatures. While this sounds painful for the creature, it just means taking the game mechanics from one creature and putting them in another. Have the stats for a lion, but not a jaguar? Copy the lion's stats, describe the jaguar to your players, and done. When I started my current campaign, I got feedback that my players want more intrigue. To me, intrigue says urban. People and factions you see over and over. But a great city is a ton of work, and I have other things to do. So I decided to reskin one of the great cities of roleplaying games: Freeport, City of Adventure.
I'm running a 13th Age / Dramasystem mashup (and testing Gods and Icons), and I want my city to be a treaty city. A city-state where the treaties that created the 13th Age were signed. And now the treaties and the age is unraveling.
So, not really a pirate city. Sure, a few pirates, but not the swashbuckling sea lords of Freeport. I put in my own ruling class to fit my plans for intrigue. The Faceless Council in place of Freeport's Captain's Council.
The Drac family's legacy of generations of pirate leaders had to go, but a ton of places in Freeport are named Drac. Spelled, backwards, Drac is Card. So Drac's End, is Card's End. That works.
My city is on a river. So I put a bridge over the river (The Glass Bridge, an ancient relic of elven glory). I take the 9 neighborhoods of Freeport (including Drac's End) and add more intrigue. Using 13th Age, I have agents of the all the Icons walking the city streets, so I look for cool NPCs and use them as Icon agents.
In this campaign, everyone knows the peace is unraveling, and all the icons are hoping to come out on top. Freeport comes with built in conflict between classes, guilds, and races. So the 13th Age Icons are trying to use those conflicts.
Even if I wanted to build your own city from the ground up (and I might), Freeport shows how to make a fantasy city work. There are many great cities in rpgs too look at for inspiration. Freeport, Ptolus, The Citystate of the Invincible Overlord, and many others.
Need your own? Try reskinning one you like.