Conjuring up a typical mediaeval city layout, here's an entire township to explore. Whilst it is given a reasonable background should you wish to use it, the actual maps are left unlabelled - save for generic indications as to possible use for each building - so if preferred you can drop it somewhere suitable in an existing campaign world. It does need to be built around a river mouth, fairly flat with forests and fields beyond the city walls, otherwise it can go most anywhere.
The suggested name for the place is Gorglis and it is supposed to be quite a haven for thieves and other urban rogues. Cramped twisty streets, houses and businesses jumbled up together, and more open areas where the rich have their palaces, courtyards with wells or fountains and more set the scene for a teeming environment where both rogues and more honest entrepreneurs can thrive. Divided into 'quarters' - distinctive areas rather than actual geometric ones - there are shipyards and other nautical establishments near the sea and on the river banks as well as areas for rich and poor to dwell. Various temples are scattered throughout, as are a wide variety of businesses (although I'm a little concerned at the juxtaposition of an undertaker's shop and a butcher!). Livestock markets (complete with stockyards), even a menagerie and theatres... and a Doge's Palace for whoever's in charge.
If you are installing the entire city 'as is' there are several essays describing the governance, buildings, docks, trade and more so you can plonk the city down and run it with little effort. There are even lists of inhabitants (mostly described by trade rather than named) that you can use to detail who is around for your characters to meet on the streets or in their homes and places of work. As a bonus, there's a collection of street names which you can apply to the city streets, which have been left unnamed.
This is a comprehensive mediaeval-style city in copious detail that should prove a joy to visit or run urban adventures through the streets.