Do you have a problem with creating a convincing-looking city for your own campaign? Did your towns looks unrealalistic? Maybe I have a solution for you.
Ancient Town-planning is a PDF file, created by a Francis Haverfield. It contains very useful information about several ancient cities. It may be very useful in designing a RPG-oriented agglomerations.
Here is a link; also it can be found in the other sources section on a sidebar.