EVANSTON, Ill. — All roads may lead to Rome, but some are much smoother than others. A new interactive map of the Roman Empire that includes roads, rivers and hundreds of sea routes allows users to calculate the travel time and costs for traversing the ancient empire. The project, called ORBIS, is allowing researchers to probe standing hypotheses and develop new ones concerning the economic, social, military and political dynamics of an empire that had a profound and enduring influence on western civilization.
The map, based on years of scholarship and new calculations, is organized around 751 sites in an area of about 4 million square miles. These sites were either prominent settlements or landmarks considered significant for traversing an empire that in its time spanned one-ninth of the Earth’s circumference and touched three continents. There are 814 road segments for a total length of 84,631 kilometers and 28,272 kilometers of navigable rivers and canals. The map even incorporates data on the strength and direction of wind and ocean currents, parameters that change drastically when a route is estimated for winter rather than summer. Different modes of travel are also included, making it possible to calculate trip time whether traveling by civilian river boat, military river boat, wagon or rapid marching.
“It’s not just an exploratory tool,” said Elijah Meeks, a digital humanities specialist at Stanford who created the map, called ORBIS, with classics scholar Walter Scheidel. “It’s also a representation of an argument.”
The network of dominant routes often changes depending on what’s being moved: There are clear military, political, economic and information networks, Meeks said. So the best way to transport a shipment of slaves from Thrace to Capua might be entirely different than the optimal route for marching a legion of troops between the same two points.
And the importance of sea routes, which traverse the Mediterranean, Black Sea and coastal Atlantic, is striking. Compared with travel by mule (20 kilometers per day for heavily loaded animals) or fast carriage (67 kilometers per day), sea emerges as the preferred mode of travel, allowing speeds of 80 kilometers per day, Meeks reported June 19 at the Leonardo satellite symposium of the International Conference on Network Science. The one notable exception is in the movement of information. A 24-hour horse relay can move information 250 kilometers in a day.
The researchers also incorporated travel costs, based on prices stipulated by an edict issued by the Emperor Diocletian in 301 that imposed price caps on more than 1,000 products and the charges for delivering them, whether by ship, donkey, camel or wagon. As is true today, the preferred route can vastly differ if time is the priority rather than expense.
“This map is really, really, really good,” said Maximilian Schich, a complex systems researcher and art historian at ETH Zurich. Scholars often focus on ever smaller entities, said Schich, when what’s needed is large-scale context. “If we don’t quantify the whole, people will carry around their image of the whole — perhaps a wrong, biased image — in their heads.”
