Ancient Roman city revealed in great detail using ground-penetrating radar

Teams from the Universities of Cambridge and Ghent discovered a bath complex, market, temple, a public monument and a sprawling network of water pipes in the walled town known as Falerii Novi, located north of Rome.

By looking at different depths, the archaeologists were able to study how the town evolved over hundreds of years.

Recent advances in ground-penetrating radar (GPR) have made it easier to explore larger areas and in higher resolution than before. It is thought the technology could have a major impact on archaeology, as it could lead to new discoveries without the complexity and delicate touch required during long digs.

GPR works like regular radar, bouncing radio waves off objects and using the ‘echo’ to build up a picture at different depths.

By towing their GPR instruments behind a quad bike, the archaeologists surveyed all 30.5 hectares within the city’s walls – Falerii Novi was just under half the size of Pompeii – taking a reading every 12.5cm.

Located 50km north of Rome and first occupied in 241 BC, Falerii Novi survived into the medieval period (until around AD 700).

The team’s GPR data can now start to reveal some of the physical changes experienced by the city in this time. They have already found evidence of stone robbing.

In a southern district, just within the city’s walls, GPR revealed a large rectangular building connected to a series of water pipes which lead to the aqueduct.

The pipes could be traced snaking across much of Falerii Novi, running beneath its city blocks rather than along its streets, as might normally be expected. The team believes that this structure was an open-air pool, forming part of a substantial public bathing complex.

The wealth of data produced by such high-resolution mapping does pose significant challenges as traditional methods of manual data analysis are too time consuming, requiring around 20 hours to fully document a single hectare.

It will be some time before the researchers finish examining Falerii Novi, but to speed the process up they are developing new automated techniques.

Professor Martin Millett, corresponding author on the study, said: “It is exciting and now realistic to imagine GPR being used to survey a major city such as Miletus in Turkey, Nicopolis in Greece or Cyrene in Libya. We still have so much to learn about Roman urban life and this technology should open up unprecedented opportunities for decades to come.”

Last month, archaeologists discovered new medieval and Roman sites while working from home by analysing data from lidar scans.