Sunken Roman road leads Venice to rethink its age

Tradition has it that the splendour of Venice grew from humble beginnings, being built from nothing by refugees fleeing the Huns and Visigoths in the dying days of the Roman Empire.

That view has been challenged by experts who have used high-tech sonar to spot the submerged remains of an ancient Roman road and harbour close to St Mark’s Square, built several centuries before the commonly accepted date of Venice’s foundation in AD421.

The research confirms theories that the Romans got there first, building a road in the lagoon and linking it to their impressive national network in the first century BC or AD.

‘‘The Venetians didn’t move to an area where there was nothing, we think there was continuity,’’ Dr Fantina Madricardo, a physicist at the Institute of Marine Sciences in Venice who worked on the project, said.

Researchers used sonar to scour the depths along the Triporti channel, which leads into the lagoon from an entrance at the Lido, one of the thin strips of land separating the lagoon from the Adriatic. Along the channel the team found 12 large structures lined up at a depth of four metres, which appear to be chunks of a 1km stretch of road.

Despite murky water and strong tides, police divers assisting the team took video of some of the structures, showing they were made up of basoli, the paving stones used by Romans to build their roads. The stones identified matched specimens brought to the surface during previous dives.

Even more fascinating for the team was the identification of a structure measuring 135m by 22m, which did not appear to be part of the road.

‘‘We think that was a section of a harbour built the Romans, although due to the shifting of the lagoon over the centuries we don’t know if it gave on to the lagoon or the sea,’’ said Madricardo, who worked with experts from Venice’s IUAV university.

What is evident is the road was linked to the nearby Roman town of Altinum, and plugged into ancient Rome’s extensive road network. ‘‘This area was crossed by travellers and sailors,’’ the team wrote in a paper published in Scientific Reports.

The finds confirmed theories developed in the 1980s by the Italian archaeologist Ernesto Canal, who suspected the presence of a road. He died in 2018.

Madricardo said: ‘‘We already know about the remains of a tower there and amphorae have been found, suggesting a settlement on the lagoon but this is the first time we have scientific confirmation. We are not sure of the date of the road, but some time in the first century BC or first century AD.’’

The road and the port are now under water because of a gradual sea level rise since the Roman era as well as erosion and subsidence constantly changing the landscape of the lagoon. ‘‘The road is at a depth of four metres, other remains in the lagoon are at two metres and the potential port structure is at 11 metres, showing how everything has moved,’’ Madricardo said.

The lagoon continues to shift shape to this day because of human intervention. At the end of the 19th century, breakwaters were built at the Lido entrance to the lagoon, which aided navigation but also caused a build-up of silt drifting down the coast from the north, Madricardo said.

The build-up led to the creation of Punta Sabbioni, a large headland opposite the Lido, flanked by the Adriatic on one side and the sunken Roman road on the other, which is now covered by fields, woodland, campsites and a beach.