The floating city of Venice hides some sunken secrets in its eponymous lagoon, ones that could quite possibly hint at its future fate.
The city, made famous by its canals, has had trouble with extreme flooding as recently as 2018 and scientists predict that the situation will only get worse as waters continue to rise. But if Venice does end up submerged in our lifetime, it will not be the first time Venetians have had to adapt to rapid climate change.
Lurking in the murky Venice Lagoon are the Atlantis-like remains of an Ancient Roman road. The discovery shows that the lagoon was once land — and it is a stark prediction of how rapidly rising water levels can obliterate even the best of human engineering and infrastructure.
What’s new — Researchers from the Institute of Marine Science in Italy have discovered 12 ghostly structures on the floor of the Venice Lagoon. Together, these structures suggest the presence of a road that was built and traversed in Imperial Rome.
Their findings, published on Thursday in the journal Nature Scientific Reports, hint at Venice’s potential future in the face of the climate crisis — but they also confirm a hypothesis first mooted in the 1970s.
The 12 structures run along a single kilometer-long stretch of the lagoon floor, indicating that a road once ran through this area — and that as recently as 2,000 years ago, the Venetian lagoon was once dry land.
Today, the Venice Lagoon, located on the coast of northeastern Italy, is 210 square miles, and on average is 34 feet deep. At its deepest, it’s 71 feet deep.
“We could identify 12 structures that there are more or less at the same depth,” oceanographer Fantina Madricardo, the paper’s lead author, tells Inverse. “We think they belong to a major infrastructure.”
To the casual observer, these “structures” just look like rocks. But if you look closer at the data, then there is evidence of a row of flat stones, which would have been the paving of the ancient road, as well as a large, cubic stone marker located nearby.
This is not the first discovery of its kind, which helps confirm that it’s likely a road. Other findings, such as a tomb on the Venetian island Torcello, indicate that what is now the lagoon was populated centuries, even millennia ago.
“From a geoarchaeological perspective, the paper details an exciting finding that sheds new light on the well-known, complex transportation infrastructure of the Ancient Romans,” Christopher Hein, a professor of coastal geology at the Virginia Institute of Marine Science, tells Inverse. Hein was not involved in the study.
How they found it — This discovery was made thanks to sonar — an acronym for sound navigation and ranging. The way it works is this: A boat carrying a large sonar instrument goes out into the lagoon. The instrument emits an ultrasonic wave into the water that’s inaudible to human ears.
“This wave propagates, hits the floor, and comes back,” Madricardo explains, describing a process called acoustic mapping.
“The time it takes to come back gives us information, since we measure the speed of sound in the water, we know what is the depth now.”
The wave is extremely high resolution and offers data every five centimeters, which allows them to build clear reconstructions of the perceived structures.
Once the acoustic mapping is done, Madricardo’s team analyzed the data from the sonar as well as from samples taken from the lagoon’s bottom to recreate the ancient road. This, Hein says, allows the researchers to “reconstruct changes in the physical environment.”
Together, these tools allow the archaeologists to “understand the changing human landscape and how it may be preserved,” he says.
Why it matters — As Hein hints, “preservation” is a key concept here. Could Venice one day resemble this road in a few hundred years? Not necessarily, but climate change certainly threatens the famous city along the canals.
Madricardo notes that this road may have sunk because it was abandoned, left to erode into the lagoon. Other populated areas of the city didn’t follow it into the depths because they have been maintained, she says. And maintained areas are built to resist subsidence, or sinking.
But it still raises the question of climate change’s influence over Venice’s future. The mean sea-level rise at the lagoon is one to two millimeters per year, according to Madricardo’s data. So while the researchers can’t say for certain why this ancient road was claimed by the sea, there’s a possibility history could repeat itself.
Hein points out that even the most permanent-seeming structures are evanescent.
“It brings into focus the ephemeral nature of human development and infrastructure along the coast,” he says.
This discovery also taps into our curiosity about the past and what we can learn from it. “Certainly there are lessons to be learned by looking into the history of human adaptation and human interaction with changing coastal zones.”
Digging into the details — Madricardo and her team actually build on decades of research by one of her predecessors, archaeologist Ernesto Canal. He pioneered work on the Venice Lagoon in the 1970s and 1980s, hypothesizing that the murky waters hid an ancient secret.
Born in 1924 in Venice, Canal spent his career scouring the Venice Lagoon for the remnants of ancient human structures. Some of his discoveries include structures near what is now Treporti, which he believed could have been the port of the City of Altino, and a number of small towers in the water, too.
As one of Canal’s disciples, Madricardo feels a strong connection to this discovery.
“This research confirms what he always knew, despite when so many did not believe him, so I’m glad to be able to remember him with this,” she says.
What’s next — This discovery calls for extensive research on the structures and what else could be lurking at the bottom of the Venice Lagoon. With more exploration, researchers might be able to recreate what modern-day Venice looked like when this road was above sea level.
Sophisticated 3D modeling could help archaeologists recreate what this road may have looked like in its prime 2,000 years ago.
“We could actually create a virtual tour of this road,” Madricardo says.
In particular, Madricardo wants to investigate one of the larger structures found, which measures 426 feet in length. Her mentor, Canal, had never talked about this structure, so it is an intriguing mystery for Madricardo and her team to investigate and continue his legacy.
She also wants to understand how this road fits into the bigger picture of Roman life during the empire’s heyday.
“It would be good to feel the puzzle and all these pieces, and understand better what was the distribution of sediments and what was the functionality of this road. This is just the first step,” she says.
Abstract: This study provides new evidence of the presence of an ancient Roman road in correspondence to a paleobeach ridge now submerged in the Venice Lagoon (Italy). New high resolution underwater seafloor data shed new light on the significance of the Roman remains in the lagoon. The interpretation of the data through archive and geo-archaeological research allowed a three-dimensional architectural reconstruction of the Roman road. The presence of the ancient Roman road confirms the hypothesis of a stable system of Roman settlements in the Venice Lagoon. The study highlights the significance of this road in the broader context of the Roman transport system, demonstrating once more the Roman ability to adapt and to handle complex dynamic environments that were often radically different from today.