From the book:
Ancient cities is an aid to help GM's creative process or it can be used as a part of any RPG product where detailed city maps are needed. If you are a GM then you may find useful the features which were planned to save you hours while you set up a town where your latest adventure takes place. It can also be a great help if you haven't prepared properly for the next meeting and need a place where your players can wander and fill up their supplies and souls.
Slavers city is an expanding community which earned it's wealth by utilizing the slaves brought here from all over the empire. Trading is also crucial to keep up the prosperity. Where's richness there are always dark figures who want a piece from the cake no matter what way...
Ancient cities 2 has some new features to add more to the gaming experience like shrines outside the city, more building types and a sewage system.