Why was Venice built on water?

Venice, with its canals, bridges and palaces suspended over the water, represents a unique historical and architectural phenomenon in the world. Considered one of the most fascinating cities in Europe, Venice astonishes with its seemingly fragile structure and its ability to endure through the centuries, despite environmental challenges. But what led its founders to build a city in the middle of the lagoon? And above all, how has it managed to remain standing to this day?

When was Venice founded?

The origins of Venice can be traced back to the fifth century AD, during the time of the barbarian invasions that followed the fall of the Western Roman Empire. Between 401 and 452, people from Roman cities in the Venetian hinterland (such as Altino, Concordia and Aquileia) began seeking refuge among the marshy islands of the lagoon, fleeing from the Huns led by Attila and the raids of the Goths. These early settlements, initially intended as temporary shelters, gradually became more permanent, eventually forming stable communities sustained by fishing, trade and lagoon-based navigation.

The symbolic founding date of Venice is traditionally held to be 25 March 421, according to certain medieval chronicles. On that day, it is said, the church of San Giacomo at Rialto, considered the city’s first religious building, was consecrated. Although this account is largely legendary, the date has become embedded in Venice’s historical identity and is still commemorated today as its moment of origin.

Why was Venice built on water?

The decision to build on an archipelago of over a hundred islands in a brackish lagoon was far from accidental. The surrounding water provided a natural defence against invading armies: marshes, shallow seabeds and shifting tides made access difficult, offering crucial protection.

Moreover, the lagoon’s strategic position enabled control over trade routes between East and West, laying the groundwork for the economic and strategic rise of the future Republic of Venice. Over time, the inhabitants reclaimed the marshland, stabilising the terrain with an ingenious system of wooden piles and stone foundations.

Why don’t Venice’s wooden piles rot?

One of the most remarkable aspects of Venice’s construction lies in the ingenious technique used to build on such unstable ground. The foundations of the city’s buildings rest on wooden piles driven deep into the mud of the lagoon, typically made from larch or oak, types of wood known for their high resistance to water.

Surprisingly, these piles don’t rot because they remain entirely submerged in water and mud, where there is no oxygen. In this oxygen-free, or anaerobic, environment, the microorganisms that would normally cause wood to decompose are unable to survive. Over time, the wood also absorbs the mineral salts from the lagoon, gradually hardening and turning into a sort of “organic stone”. It’s this extraordinary method that has allowed Venice’s palaces to stand firm on their ancient foundations for centuries.

How drinking water came to Venice

Living surrounded by brackish water presented a considerable challenge: securing a supply of drinking water. From the earliest days, Venetians devised an ingenious system of public and private cisterns designed to collect and filter rainwater. The courtyards of Venetian buildings (many of which can still be seen today) were built around a central well. Surrounding this, layers of sand and gravel acted as natural filters, purifying the rainwater before it was channelled through underground conduits into sealed, waterproof cisterns.

It wasn’t until the 19th century that a more modern aqueduct system was introduced. Today, Venice receives its drinking water through a piped network connected to the mainland. Nonetheless, the legacy of the cisterns remains a lasting symbol of Venetian ingenuity.

What is the phenomenon of subsidence?

One of the most serious threats to Venice’s survival is subsidence, the gradual sinking of the ground, a natural process that has been exacerbated by human activity. Natural subsidence occurs as the lagoon’s soft sediments, on which the city is built, slowly compact over time. However, from the twentieth century onwards, the extraction of groundwater from beneath the lagoon for industrial purposes accelerated the phenomenon, causing the ground to sink by more than 20 centimetres in under a hundred years. The combined effect of subsidence and rising sea levels, the latter driven by global warming, makes the city particularly vulnerable to acqua alta, the periodic high tides that flood the city’s streets and squares, including the iconic St Mark’s Square.

When will Venice disappear?

The prospect of Venice slipping beneath sea level is deeply unsettling and, unfortunately, not beyond the realm of possibility. Recent studies suggest that, without substantial efforts to tackle global warming, sea levels could rise by between 60 and 100 centimetres by 2100. Such a scenario would seriously threaten the city’s habitability, demanding large-scale, costly structural interventions.

The much-publicised MOSE system, first activated in 2020, remains the primary defence against rising sea levels. This network of mobile barriers, positioned at the lagoon’s inlets, is raised during exceptionally high tides to protect the city. Yet it is becoming increasingly evident that even MOSE may not be enough. Without bold action on climate change, more sustainable tourism policies, and improved stewardship of the lagoon’s fragile ecosystem, Venice could face the very real risk of becoming uninhabitable.

Article translated by Agnese Giardini

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