Augustus, ancient Rome's first emperor, placed a gilded monument called the Milliarium Aureum, or Golden Milestone, in the Roman Forum in 20 BC to mark the symbolic starting point for all roads in the sprawling empire. These roads indeed were the backbone of the world's first continental-scale transportation system. Now, researchers have conducted a detailed structural analysis of the empire's road network, spanning roughly 190,000 miles (300,000 km) of routes crisscrossing Europe, the Middle East and North Africa... The researchers also documented a correlation in many regions between the old Roman roads and modern highways... Some roads were very durable,...