If you have the time or the patience this would be a really neat project to complete, especially if the place has meaning to you!
1) Find a detailed (but not too detailed) map of your city of choice.
2) Use a thin black marker and a ruler to emphasize the lines that you are going to cut out. (Leaving just the streets.)
3) Scan the map (with your markings) onto your computer and flip the image (so that the correct side will be outwardly facing when you mount it.)
4) Grab your exacto knife and cut away!
5) Spray adhesive onto your freshly-cut map and mount it. Enjoy!