The transport system of the Roman Empire was a reflection of the geographical characteristics and constraints of the Mediterranean basin. The Mediterranean Ocean provided a central role in supporting trade between a network of coastal cities, the most important of the Empire (Rome, Constantinople, Alexandria, Carthage, etc.). These cities were serviced by a maritime and road network permitting trade within their respective hinterlands. Little fluvial transportation took place since the major pan-European rivers, the Rhine and the Danube, were military frontiers, not the core of the empire.
The road served numerous functions, such as military movements, political control, cultural and economic (trade). Road management and maintenance fell into four categories; via publica (main public roads crossing provinces), via militaris (maintained for military purposes), via vicinalis (provincial roads that were connectors between towns and main roads), via privata (managed by private land owners but public of access). To improve the traveling speed, posthouses with fresh horses were laid every 15 kilometers along the route, and lodgings for travelers could be found about every 40 kilometers. This 40 km corresponded to the average distance a traveler could cross each day. Courier services could travel twice that daily distance. Since maritime transport was more efficient than road transport, it was less costly to ship grain from Egypt to Rome than to service Rome by road transport from other nearby areas of Italy. The notable exceptions were the Nile and the Rhone rivers.
The Appian Way (Via Appia), about 560 kilometers in length, was one of the first Roman roads (Via) to be constructed (around 312 BC) under the initiative of emperor Appius Claudius Caecus. It linked Rome to Brundisium (Brindisi). As the empire grew, this system was expanded to cover 80,000 kilometers of first class roads at the height of the Roman Empire (around 200 AD). Most of the roads were constructed by soldiers, prisoners of war, and slaves. The minimum requirement of a first class road was a width of 5 meters and a drained stone surface. The Romans also built the world’s first dual carriageway, Via Portuensis, between Rome and its port Ostia at the mouth of the Tiber.
The Roman Road network covered most of the conquered provinces, with Rome as the focal point (thus the saying “All roads lead to Rome”). At the center of Rome was located the milliareum aureum (the golden milestone), from which the Roman roads radiated. Way stations where travelers could rest and eat dotted the network. The system collapsed during the Middle Ages because of the lack of maintenance and plundering of construction materials. However, the remains of the Roman network provided transportation in Europe for a thousand years. Only small segments of this system are left today.