Impressive map of the United States showing only all roads and streets in the country. 240 million individual road segments—according to the its creator Fathom Information Design—and nothing else. It's amazing how you can see all the geography contours. Check out the details:
Roadless terrain forms the topography of the Appalachian Mountains.
A detail of the West Coast shows the relative lack of roads in mountainous areas, punctuated by the densely populated Bay Area.
You can buy the print here.
For comparison, here's Germany's. Expand this one to see the roads up close.