From Kottke.org:

A subway-style map of Roman Empire roads circa 125 A.D.

After much research, Sasha Trubetskoy has completed a subway-style map of the road system of the Roman Empire. From about 300 BC, the Romans built or improved over 250,000 miles of roads (50,000 miles were stone paved) that extended into the farthest reaches of the Empire: from Spain to modern-day Iraq to Britain to northern Africa.

I’ve reprinted it here, but click on the link above to see it in greater detail.