Researchers also discovered the location of the town's theatre, marketplace and other buildings, which disappeared after its abandonment, a release from the University of Cambridge said today.
Originally founded as a Roman colony in the 4th century BCE, the site of Interamna Lirenas lies in the Liri Valley in Southern Lazio, about 50 miles south of Rome itself.
After it was abandoned around the year 500 CE, it was scavenged for building materials and, over time, its remains were completely lost from view.
Today, the site is an uninterrupted stretch of farmland, with no recognisable archaeological features, the release added.
Researchers have successfully produced the first images of the ancient site, using geophysical methods that allowed them to look beneath the surface of the earth and map the layout of the entire settlement, which spans 25 hectares.
The resulting pictures have already thrown up a few surprises.
Earlier scholars had previously imagined that the Roman town of Interamna Lirenas was something of a sleepy backwater, but the large marketplace and theatre instead suggest that, in fact, it was a bustling economic and social centre in its own right.
"Having the complete streetplan and being able to pick out individual details allows us to start zoning the settlement and examine how it worked and changed through time," Martin Millett, Laurence Professor of Classical Archaeology at the University of Cambridge and Fellow of Fitzwilliam College, said.
"It shows that this was a lively and busy place, even though most scholars have reckoned that it was marginal and stagnating.
We have also carried out research in the surrounding countryside which adds to the picture because it shows that the nearby farmland was thriving as well."
The images are the result of a project which began in 2010 that aims to understand more about what happened in towns established by the Romans as colonies in Italy following her conquest, the press release said.
