In a clever bit of technological legerdemain, Stanford University has combined historical research, mapping, and Web technology to bring ancient Roman Empire travel to the Internet. A cross-disciplinary team has created and launched ORBIS: The Stanford Geospatial Network Model of the Roman World. With it, a user can determine how long it will take to travel from any point in the Roman Empire to any other, as well as calculate the cost of transporting goods and people.

This heretofore unnatural union of geographers, technologists, and historians of the ancient world is becoming more and more common under the descriptor of "digital humanities." ORBIS looks to be one of the most effective examples of its promise.

Built by historian and classicist Walter Scheidel and Stanford Libraries' digital humanities specialist Elijah Meeks, with the assistance of geographer and Web developer Karl Grossner and GIS analyst Noemi Alvarez, the interactive online atlas is based on a host of data. This includes historical tide information and weather; size, grade, and surface of roads; main cities and ports; land, sea, and river routes; vehicle speed (including ships, ox carts, horse, and walking); and the cost of transport.

The time period the system centers on is about 200 CE, when Roman power was at its highest and the empire's extent was greatest. The atlas is built from 751 sites, most of which are cities and towns, and covers about four million square miles. Two hundred sixty-eight of the sites are ports. The road network mapped on ORBIS includes 52,587 miles of road, including desert tracks and 17,567 miles of rivers and canals.

The dynamic distance cartogram

According to Meeks, the project started when Scheidel happened to see a dynamic distance cartogram of the London tube system. Dynamic distance cartograms distort the layout of their data based on your selection. If you choose one stop, it will show you a map of how close in time expenditure the other stops are, based on information like train connections.

"In building a geographic transportation model of the Roman Empire, you can't just download an API for distance," Meeks told Ars. So once the proposal was approved, the principals had to figure out how to collect that data. For land travel, they were able to use itineraria, Roman accounts of time spent traveling various routes. But for sea voyages, similar information did not really exist. It was in creating a model for the missing information that ORBIS's builders found themselves in the role of pioneers.

They had to write a model for ancient sea travel based on scientific data regarding wind, currents, and weather. Meeks did so using Gephi, the agnostic network analysis and visualization tool. He subsequently imported it into PostGIS, a PostgreSQL open-source database.

Grossner built the user-facing site using ExtJS for the site interface and OpenLayers for the maps.

"As a geographer, my favorite thing about the site," Grossner told Ars, "is that it brings some basic geographic principles, like cost distance and cost surfaces, to an audience that seems genuinely tickled by them. The oddball merging (of the site's textual components with its interactive ones) was done with enough care that the approach can be fairly evaluated as a potentially new wrinkle on an emerging genre of interactive scholarly works."

History as a system

The major ground broken with ORBIS, however, is not technical, per se. It's in the use of technology to approach history as a system instead of a static collection of data.

"When you look at other historical digital projects," said Meeks, such as Pleiades, the crowd-sourced digital atlas of ancient history, "you see sets of rich data layers you can look at on maps, which is great. But with ORBIS we have a model of an historical world system—we can start to talk about how this world functioned."

In only two weeks since its launch, the response to ORBIS has astounded its builders.

"We've gotten feedback from middle school teachers, PhD candidates, undergraduates using it for papers." Respondents have noted that in addition to being a good tool for teaching the history of Rome, it's equally good at teaching geographical concepts. One scholar is using it to determine the cost of information distribution in the ancient world. Another is using it to track the journeys of St. Paul. "It's proving to be a useful tool on various levels, and so popular I'm not even sure our little server is going to be able to handle it."

One of the disappointments for Meeks, however, is the tool that inspired the ORBIS project in the first place.

"A tech friend of mine was laughing at the metrics," Meeks said. "It'll show 50,000 people looking at the maps but only 100 using the interactive distance cartogram." In fact that function is not very intuitive looking. At first (or even second and third) glance a first-time user is not sure what he or she is looking at.

"It shows me that we in the library business have to take UX design seriously."

This is a shame—albeit one likely to be mitigated with subsequent design tweaks—because it is arguably the most valuable aspect of the project.

The season, the city, the cost

If Web technologies only made what is in books available online, it would still be important because of how that act democratizes access to information. But when it does something simply impossible within the pages of a book, it gets a great deal more exciting. ORBIS's cartogram is just such a thing. It allows the user to select one main city—Rome, Constantinople, London, or Antioch—and a season, then choose either the fastest routes or the cheapest ones. The map changes dynamically according to those choices, and rearranges the spatial relationships to reflect them.

Suddenly London zooms away from Rome, actually moving off the map—it's nearly impossible to get there during the winter due to Atlantic storms. With another set of choices, Corinth meets Antioch in the center of the map—it's a cheap destination during the summer.

At moments of innovations such as this one, history seems closer and technology more relevant.