FYI: I originally created the map a few years back, so for the purposes of this instructable, I'm creating a smaller example for the step by step instructions.
Step 1: Gather Supplies
map (It's important that the map be a detail of a city so that the streets are large enough for you to cut around. My large map was a tourist map from a hotel that I got when traveling. The example in the following steps was printed from an online map.)
paper larger than map (I originally chose to use plain white paper for a minimalist effect, but since my second map is much smaller, I decided to use a magazine image from a large fashion magazine. I would have loved to use an image of the town in the map. Perhaps someone else would like to go that route.)
Step 2: Placement
If there's an image on the front, use a window to see through the papers and make sure it's placed the way you want.
I used masking tape, but just about any type that will cut easily with an x-acto would work.