The ancient Roman road system is one of the best-documented engineering achievements of the ancient world, and also one of the most practically influential: sections of Roman road are still in use, Roman alignments survive in modern road networks across Europe, and the engineering principles were not substantially improved upon until the 18th century.

The basic construction method — layers of increasingly fine material on a compacted foundation, with a cambered surface for drainage — varied by region and available materials but followed consistent principles documented in Vitruvius and confirmed by archaeological cross-sections. The surveying technology used to maintain straight alignments over long distances in varied terrain is still not fully understood; Roman surveyors used a tool called a groma for right-angle measurement and probably some form of leveling instrument, but the details of how they achieved the precision they did are not fully documented.

The road network's military function is obvious — rapid troop movement and supply chain maintenance. The economic function is equally important but harder to quantify. Travel speed on good roads roughly doubled compared to cross-country movement; the ability to transport bulky goods (grain, timber, building stone) over long distances at reasonable cost changed the economic geography of the empire. Regions that had been subsistence agricultural could participate in a wider market economy when road access made transport costs manageable.

The staging posts (mansiones) along major roads — providing accommodation, fresh horses, and basic services — were a state-maintained infrastructure investment that subsidized both official and commercial traffic. The cursus publicus (state courier service) that used these facilities moved official communications at remarkable speed for pre-modern technology: perhaps 50-80 km per day for ordinary couriers, faster for urgent relays.