A new map and digital dataset called Itiner-e increases the known length of the Roman Empire's road system by more than 110,000 km.
Itiner-e is the most detailed and complete open digital dataset of roads throughout the Roman Empire. Image credit: de Soto etc.., two: 10.1038/s41597-025-06140-z.
At its peak in the second century AD, the Roman Empire numbered more than 55 million people and stretched from modern Britain to Egypt and Syria.
Although the network of roads throughout the Empire contributed to its development and maintenance, it remains incompletely mapped and existing digitized images are of low resolution.
“The study of the roads of the Roman Empire is a centuries-old endeavor,” said Aarhus University researcher Tom Brugmans and his colleagues.
“There is a wealth of information about roads that have been physically identified through archaeological excavations and surveys, about milestones that were located at regular intervals along Roman roads, and about historical sources such as the Antoninus Route or Tabula Peitingeriana describing the main connections between settlements, as well as detailed regional summaries of Roman roads.”
“However, finding and locating this diversity of research and the spatially precise location of the roads themselves is hampered by the lack of empire-wide synthesis and digitization.”
The researchers created Itiner-e using archaeological and historical records, topographic maps and satellite imagery.
The dataset includes 299,171 km of roads – more than the previous estimate of 188,555 km – and covers almost 4 million km.2.
Scientists attribute this increase in road coverage to the wider coverage of roads in the Iberian Peninsula, Greece and North Africa, as well as the adaptation of previously proposed road routes to geographical realities.
This includes allowing roads crossing mountains to follow winding paths rather than straight lines.
Itiner-e includes 14,769 road sections, of which 103,478 km (34.6%) are major roads and 195,693 km (65.4%) are minor roads.
The exact location of only 2.7% of roads is known with certainty, 89.8% is less certain, and 7.4% is inferred.
“Itiner-e represents the most detailed and comprehensive public digitization of the roads of the Roman Empire, and also identifies gaps in current knowledge of the road system,” the authors said.
“They note that Itiner-e cannot show changes in the road system over time and that future research is needed to examine this across the entire Roman Empire.”
“Itiner-e could be used in future studies examining the impact of Roman roads on transport, governance, migration and disease transmission in the Empire.”
The map and dataset have been described in paper in the magazine Scientific data.
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P. de Soto etc.. 2025. Itiner-e: A high-resolution Roman road dataset. Scientific data 12, 1731; two: 10.1038/s41597-025-06140-z
