Historic palaces, canals instead of streets, the world-famous carnival and luxurious masks, and the spirit of real Italy… Without a doubt, Venice is one of the most famous Italian and even European cities. Among the many symbols of this Italian gem, gondolas and canals occupy a truly special place. Still, there is increasing talk about the disasters that often strike it. Questions arise about how Venice was built, what is behind its construction techniques, why it sank, and whether this process can be stopped. The city is sinking due to a combination of natural and human factors. Although a complete stop to this process is not likely, it is possible to slow it down and control it.
The city of Venice is famous worldwide for being an engineering marvel. Though it has terrific food, great local artisans, and beautiful architecture, it is most famous for being built on water. So precisely why and how was this ancient city built?
Why did people move to Venice?
*When the Roman Empire collapsed in the 5th century A.D., Italy was no longer a safe place to live. Without a strong military, the barbarian tribes from Germany and Eastern Europe could invade Italy. In fear, people fled their homes on the mainland for the seclusion of the lagoon. They used the marshy lagoon for protection and found refuge among the poor fishermen. As the invasions continued across Italy, more refugees joined the first settlers, and the need to build a city grew. According to legend, Venice was founded at noon on Friday, March 25th, 421 AD, close to the Rialto Bridge (and has just celebrated its 1600th birthday!).
*Source: livtours.com
How was Venice built?
Contact with water
This engineering marvel on the water was built on the extremely unstable soil of the lagoon, namely layers of silt and sand. These layers were not designed to bear the weight of stone palaces and churches. Centuries ago, Venice was constructed on thousands of wooden piles driven deep into the soft ground to be habitable. They assembled wooden platforms on these pencil-shaped stakes before constructing buildings above them. The enduring nature of Venice’s wooden foundations has fostered the belief that wood buried in muddy ground stays preserved.
These pillars served as the foundation for monumental buildings. Istrian stone, an impermeable limestone quarried in Istria, Croatia, was often used at the lower levels of building foundations, where the structure came into direct contact with water. Despite the ingenious construction method, the ground slowly but inevitably sank under the weight of the buildings over the centuries. This process, known as natural subsidence, is one of the key reasons Venice is sinking today.
Drinking water supply
The city has always struggled to find drinking water. It has wells, but they are no longer functional because drinking water is transported from the mainland through large pipes along the bridge.
What was the duration of Venice’s construction?
Building this beautiful city was a monumental task that spanned generations. The initial settlement in the 5th century began with wooden houses built on posts driven into the lagoon’s sandy bottom. Over 400 years, the people of Venice slowly created a distinctive foundation system by employing millions of wooden piles to uphold stone structures. Each central structure required years of careful engineering to ensure stability in the challenging lagoon environment.
Why is Venice sinking?
Industry
In the second half of the 20th century, industrial development around Venice brought unintended consequences for the city. Numerous plants pumped groundwater to meet production needs. This unwittingly disrupted the fragile balance of the soil on which Venice rests. Removing water from the layers beneath the city further destabilised the ground. This accelerated the subsidence process. Although pumping was stopped in the 1970s, the damage had already been done—Venice had already irreversibly lost some of its height relative to sea level. This unfortunate change directly results from construction techniques and the city’s original construction.
Water level
It’s not only the city sinking into the ground—it’s primarily the rising water levels surrounding it. In addition to natural subsidence and the consequences of human intervention, Venice is now facing another serious challenge: climate change. Because of global warming, water levels are rising, worsening the city’s fragile stability. The tides are increasingly crossing the coast. The “acqua alta,” known in Italy as “high water,” is becoming more frequent and destructive.
Acqua alta (“high water”) in Venice occurs between autumn and early spring; flood tides pushing in from the Adriatic often threaten the city. This threatens daily life and the city’s future on the lagoon. This is especially alarming considering how they managed to build Venice on such unstable ground.
Can this process be stopped?
MOSE project
It is impossible to stop Venice’s sinking completely, but its pace can be significantly slowed. The ambitious MOSE project (Modulo Sperimentale Elettromeccanico – The mobile barriers for protecting Venice from high tides), a system of movable dams installed at the three main entrances to the Venetian lagoon, plays a key role. The flood barrier at the lagoon’s entrance became operational in 2020. When a tidal threat is announced, the dams are raised, physically preventing the sea from entering the city.
Although MOSE (Modulo Sperimentale Elettromeccanico) does not solve the subsidence problem, it has proven to be a strong defence against floods, which were once inevitable. The system was first activated in 2020, and the results have been encouraging. Namely, Venice has remained dry during several large tidal waves.
Various projects
Another critical step in preserving Venice was in 2021 when the Italian government banned large cruise ships from entering the city’s historic center. This decision was made to protect cultural heritage because of the vast masses of ships’ concrete impact on the lagoon. They create strong waves that further erode the coast and encourage erosion of the foundations. By removing cruise ships from the most sensitive parts of the city, the harmful pressure caused by how Venice was built on the fragile system that keeps it above water is reduced.
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Finally, it is worth mentioning that the authorities are carrying out various experimental projects to “raise” some parts of the city using special techniques. The mayor assured that work on the flood barrier would proceed, while the Prime Minister stated that the government would accelerate the project. However, this is technically and financially (for now) very demanding, considering how Venice was initially built on unstable soil.