The technology of surfaced paths connecting human settlements — one of the oldest and most consequential investments any civilization makes, the infrastructure through which trade, armies, messages, and ideas move, and a technology that has organized the political geography of every complex society from ancient Mesopotamia to the modern highway system.
All roads lead to Rome — but the Roman roads also led away from Rome, into every province of the empire. This is the paradox of road infrastructure: it connects, but connection runs both ways. The roads that let Rome project military power into Gaul and Britain also let merchants bring goods to Rome, let ideas travel from Greece and the Near East into the Latin world, and eventually let the Germanic peoples who ended the empire move into it. Roads do not respect the intentions of those who built them. They enable everything — trade and invasion, communication and contagion, pilgrimage and flight.