Digital Geography

What is better: a map or a picture?

I was reading an article entitled “China, the megalopolis of 110 million inhabitants that impresses the world” on a popular online journal (see article) and after a dozen lines read: “Beijing is already surrounded by six ring roads, [… ] but the seventh will be 940 kilometers long.” How many are 940 km for example along a circle, as the Circular Highway¬†of Milan?