The Mesopotamians may have built the first roads, and India's Mauryan civilization had a sizable network of roads by 400 B.C. The Persians built the first highways circa 500 B.C., running from Asia Minor to India, primarily to serve military and administrative needs rather than trade or routine travel. The ancient Chinese also boasted a highway system, while the Greeks, wary of disturbing the natural landscape, which they believed was the habitat of supernatural entities, constructed few major roadways.

The Romans had no such reservations, and their highway system—some of which is still is use today, so well was it constructed--was fashioned of stone blocks covered with sand or broken stones and embraced 50,000 mi. (80,000 km) of roads, complete with drainage systems and stair step mounting stations. Rome's decline in the fourth century A.D. heralded the onset of fourteen hundred years of neglect of...