“all roads lead to Rome!” Roads were the lifeline of the Roman Empire, stretching from Britannia to North Africa – people settled along those roads; Armies, travelers, goods, knowledge, and power traveled with them to the farthest corners of the empire. To this day, the Roman road network continues to shape large parts of Europe, the Middle East and North Africa.
Now, a huge new digital research project is fundamentally changing the way we look at that ancient infrastructure. The international academic team behind the Itiner-e project has created the first high-resolution open-data set mapping the entire road network of the Roman Empire. In total, they have been able to digitally map 299,000 kilometers (186,000 miles) of roads crossing some 4 million square kilometers of the former empire – almost double the length of roads previously thought to have existed.
Itinerary-e: Digital Mapping of the Ancient World
To digitize the network, reliable sources were studied. Researchers combed through archaeological sites, travel journals and centuries-old road maps, such as the Tabula Peutingeriana. The historical clues found were compared with modern aerial and satellite imagery to create Itiner-e.
Traces of previous divisions of land (centuriation) – identified not by walls or ditches but by parcels, as the Romans alike divided new and conquered territories into orderly rectangular plots – whose checkerboard patterns are still recognizable today as paths, roads or boundaries. Those patterns are still easily recognizable on aerial photographs, cadastral maps, and even on foot; Especially in northern Italy, southern France and Tunisia.
In the end, the researchers assembled 14,769 individual segments into a highly detailed (accurate to 50 meters or 164 feet) geoinformation system, or GIS – meaning that every single segment of road is linked to regional metadata, quality indicators, sources and a digital link to information on former ancient settlements. It provides, for the first time, a more comprehensive understanding of how mobility, administration, and even disease was distributed within the empire.
Digital methods and archaeological detective work
In addition to covering more than 100,000 kilometers of main roads, the researchers also mapped another 195,000 kilometers of secondary roads, visualizing mobility in the farthest and shortest reaches of the empire.
Another new impulse provided by the team was the use of digital models to simulate the speed, route and physical obstacles of paths passing through difficult terrain.
Roads: the foundation of power and mobility of the Roman Empire
Another novelty of Itiner-E is that it also shows how the logistics capacity of the Romans allowed the massive expansion of their empire – making trade, intellectual exchange, and military control over vast lands possible. The over 100,000 kilometers of main roads that ran through the empire were dotted with mile markers, military targets and administrative centres, and thus were well documented.
The expansion of secondary roads reflects growth in regional economies and everyday mobility. In evaluating the data, the researchers found that some areas still have clear traces of the network today, while others have been reconstructed with digital demarcations based on regional historical past. Overall, this project opens the door to potentially fruitful future investigations.
Mapping the unknown: why Roman roads remain mysterious
Itiner-e Road Atlas The history of uncertainty also tells the story – although most roads can be found documented in written sources, their exact routes are often unknown. This is due to various details, or to topographic changes over the centuries and the natural expansion of the road network.
Researchers say only 2.7% of the roads can be mapped with archaeological certification. In about 90% of cases, researchers can only pinpoint a “likely” route. When it comes to the final 7.4% of roads, scientists can only suggest “hypothetical” routes that the roads would follow.
The map’s data set presents it transparently in its “confidence maps”, which is fairly new to archaeological research. These maps highlight specific areas or road sections that could use improvements in their archaeological excavation sites as well as mapping sources.
Re-measuring Roman roads means rewriting European history
One thing the Itiner-e project makes clear is that the roads of history are much longer and more labyrinthine than previously thought.
With this, researchers have uncovered massive gaps as well as opened up new avenues for exciting stories and insights. Every archaeological gap is an invitation to continue digging.
This article was translated from the original German by John Shelton