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 study showed the old adage "all roads lead to Rome" was not exactly true, and the empire's later imperial capital Constantinople — present-day Istanbul — was a better fit for that maxim. While the Romans preferred building straight roads, difficult terrain sometimes frustrated that goal, it found.
The researchers also documented a correlation in many regions between the old Roman roads and modern highways.
The Romans, master engineers and builders, constructed roads stretching from the Moroccan and Arabian deserts in the south and east, all the way to Scotland and the Atlantic Ocean in the north and west. These roads were linked to navigable rivers and sea lanes to form a comprehensive transportation web.
"This infrastructure meant that a vast region became more tightly integrated: it provided a continent-sized platform for people, animals, pathogens, goods and ideas to spread," said classical archaeologist Tom Brughmans of Aarhus University in Denmark, who helped lead the study published on Tuesday in the journal Nature Communications.
"The Roman legions marched over roads to respond to threats, relieve colleagues and colonize new territories. Radical new ideas like early Christianity moved with people over land and sea. But the roads themselves were most used for the frequent commutes between farm and field, or to local markets for selling produce," Brughmans said.
Some roads were very durable, constructed with a combination of materials including crushed stone, lime cement, gravel and paving stones. Traffic consisted mostly of people walking and riding on animals including horses, donkeys, mules and camels, as well as pack animals and animal-drawn carts and carriages.
Road distances from Rome were measured from the Milliarium Aureum. But was this ancient megalopolis really the center of the network?
"All roads lead to Rome? Not really," Brughmans said. "Rome is centrally located for Mediterranean shipping, but not particularly central in the Roman road system. We found that provincial capitals were exceptionally well located on the roads in their province, facilitating effective provincial administration and tax collection."
Some of these provincial capitals included Ankara in Turkey, London in Britain and Corinth in Greece.
"Rome itself was centrally located on the roads on the Tyrrhenian coast of Italy. But when we consider all movement within the entire Italian peninsula, we were shocked to discover that the most central road actually follows the opposite Adriatic coastline, bypassing Rome altogether," Brughmans said.
A NEW CAPITAL
In the early fourth century AD, the Emperor Constantine moved the capital to Constantinople.
"This new capital was strategically located where Europe and Asia meet, and our research has revealed that it was exceptionally central for empire-wide overland travel — way more so than Rome," Brughmans said. "It's on the Bosporus, and we know of ferries that crossed this strait in antiquity, effectively connecting European and Asian road traffic."
Roman engineers used tools and techniques to make roads as straight as possible, with the Via Appia south of Rome a prime example.
"But even the Romans had to bow to nature. We found that Roman roads tend to be straight only if the local topography allows for it, such as in the rather flat areas of Belgium, northern France or the Po Valley in Italy. On the whole, they did not move mountains just to build a road," Brughmans said.
These ancient roads structured interactions among hundreds of millions of people for more than two millennia, given the continued use of many long after the Western Roman Empire fell in 476 AD and the Eastern Roman Empire, also called the Byzantine Empire, succumbed in 1453.
"The persistency of the Roman road network can be demonstrated for many regions, from Britain to the Near East," said Adam Pazout, a postdoctoral fellow at the Autonomous University of Barcelona who helped lead the study. "And these roads in many places served as the main communications throughout the medieval period until development of the railroads in the 19th century and highways in the 20th century."
Many modern highways trace ancient roads.
"A great example is the Via Augusta, which goes from Cadiz in the south of Spain to the Pyrenees. The road passes under a triumphal arch called the Arc de Bera between Tarragona and Barcelona, where you can clearly see it has the same course as the modern N-340 motorway," Brughmans said.
