This book gives a detailed overview of a city. The material is rules-edition neutral for the most part and could be used with 3.5, Pathfinder, or 4th.
If you are running the Curse of the Crimson Throne adventure path, you will find this book invaluable, as many of the adventures take place within the city. Otherwise it is still an excellent drop and use city for any DnD themed campaign.
The book gives several good maps, and a breakdown of each section of the city. It lists major locations, along with notable NPCs, but leaves plenty of room for you to add your own.