Welcome to the Guild PapaBundy! Well there are some wonderful tutorials here that can help get you up to speed with regard to the how-tos of digital mapping. That being said, most of the city maps and all of the town map tutorials here are of a medieval fantasy variety, so you will have to modify them to suit your purposes. This will be challenging but also gives you a unique opportunity to contribute something novel to the community here. My advice would be to browse through the tutorials section and study all of the town maps there. Second, if you don't already have Google Earth, download it to your computer and use it to zoom in on various cities around the world. Studying these will give you a good feel for layout and architectural design from a birds-eye view. Finally, the best (and well, only) example I know of a modern city map done here was made by mearrin69. Here is a link to Mearrin's Tarina map. It might be too high of a target for you to shoot for just yet but it can serve as a source of inspiration. Hope that helps.