Archaeologists have documented the presence of an about 1,200-m-long segment of an ancient Roman road on a beach ridge now submerged in the Venice Lagoon, the largest lagoon in the Mediterranean Sea, surrounding the historical city of Venice in Italy; its presence confirms the hypothesis of a stable system of Roman settlements in this area.

The position of the paleobeach ridge in the Treporti Channel in Roman times (in yellow in transparency over the current satellite data) and the alignment of Roman stone remains and levee road (red dots and lines), buildings (green squares) and brick walls (white pentagons); the pink solid line indicates the position of the structures reconstructed by Madricardo et al. Image credit: Madricardo et al., doi: 10.1038/s41598-021-92939-w.

“The Romans built a very efficient road system extending for tens of thousands of kilometers to connect all their territories,” said Dr. Fantina Madricardo from the CNR-National Research Council at the ISMAR-Marine Science Institute and colleagues.

“Several portions of this ancient road network are still well preserved after more than two millennia in many archaeological sites in Europe, the Middle East and North Africa.”

“The transport system, however, was not limited to the routes on land, since the imperial control of the territory extended to transitional environments such as deltas, marshes, and lagoons and a capillary network of waterways was used for the exchanges of goods and the movement of people.”

“We know that in Roman times, the relative mean sea level was lower than today and large parts of the lagoon, which are now submerged, were accessible by land.”

“The fate of the Venice Lagoon, its origin and geological evolution have always been tightly linked to the relative mean sea level rise, that is now threatening the existence itself of the historical city and the lagoon island.”

Reconstruction of the Treporti Channel paleobeach ridge and the Treporti Channel road (TC road) in Roman times: (a) from an aerial perspective, with the Venice lagoon to the left and the Adriatic Sea to the right; the position of the TC road corresponds exactly to the position of the archaeological structures mapped, whereas the extension of the TC paleobeach ridge is only hypothetical since the area has been radically modified over the centuries; (b) a zoom-in view and (c) section of the TC road based on the stratigraphy of the cores extracted under the basoli. Image credit: Madricardo et al., doi: 10.1038/s41598-021-92939-w.

Mapping the Venice lagoon floor using sonar, Dr. Madricardo and colleagues discovered 12 archaeological structures aligned in a northeasterly direction for 1,140 m, in an area known as the Treporti Channel. The structures were up to 2.7 m tall and 52.7 m long.

Previous surveys of the Treporti Channel uncovered stones similar to paving stones used by Romans during road construction, indicating that the structures may be aligned along a Roman road.

The archaeologists also discovered an additional four structures in the Treporti Channel that were up to 4 m tall and 134.8 m long.

Based on its dimensions and similarity to structures discovered in other areas, the largest of these structures is thought to be a potential harbor structure, such as a dock.

Previously collected geological and modeling data indicates that the road is located on a sandy ridge that was above sea level during the Roman era but is now submerged in the lagoon.

The findings suggest that a permanent settlement may have been present in the Treporti Channel during the Roman era.

“The road may have been linked to a wider network of Roman roads in the Italian Veneto Region and may have been used by travelers and sailors to journey between what is now the city of Chioggia and the Northern Venice Lagoon,” the researchers said.

A paper on the findings was published in the journal Scientific Reports.

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F. Madricardo et al. 2021. New evidence of a Roman road in the Venice Lagoon (Italy) based on high resolution seafloor reconstruction.