Ancient Road Networks

Road networks were among the most consequential technologies of the ancient world. They enabled the movement of armies, merchants, messengers, and ideas across vast distances, binding diverse territories into coherent political and economic units. The scale and sophistication of ancient road building remains impressive by any standard.

The Persian Royal Road, built by Darius I around 500 BCE, connected the Achaemenid Empire's administrative centers over a distance of 2,700 kilometers from Susa to Sardis. Relay stations with fresh horses allowed royal messages to cover the entire distance in about seven days — a speed that would not be regularly surpassed for over two thousand years. The Chinese Qin and Han dynasties built extensive road networks to connect their unified empire, including roads through mountainous terrain that required remarkable engineering.

The Roman road system was the ancient world's largest and most sophisticated. At its peak, it comprised over 400,000 kilometers of roads, including 80,000 kilometers of paved highways. Roman roads were engineered for durability: multiple layers of gravel, sand, and stone, with drainage ditches on both sides. Their primary purpose was military — enabling rapid troop movement — but they also facilitated trade, communication, and cultural exchange. Many European highways still follow routes first laid out by Roman engineers.