Mose: The Epic Story of the Infrastructure that Protects the Venetian Lagoon from Tides

No one believed in it anymore. For years, Venice’s Mose barrier system was synonymous with debates, clashes, delays, and waiting that seemed endless. A critical infrastructure project that many considered useless, harmful, even dangerous to the natural balance of the Venetian lagoon.

Yet, that system of 78 yellow gates, installed at the inlets of Lido, Malamocco, and Chioggia, now keeps the most beautiful and fragile city in the world dry. Since it came into operation, the Mose has protected the Italian water city dozens of times, repelling tides that in the past would have flooded alleyways, squares, churches, and museums. It is the paradox of a work born amid criticism and transformed into a symbol of tangible salvation.

Venice was born on water, and in water it built its destiny. But that destiny, in recent decades, has turned into an increasingly frequent nightmare. On 4 November 1966, the city awoke submerged under almost two metres of water. A tide of 194 centimetres – the highest in history – which overwhelmed everything: churches, palaces, shops, archives.

It was then that Italy understood that the survival of Venice was no longer guaranteed. The lagoon was sinking due to subsidence, while the sea level was rising, and each year the risk of a new catastrophe drew closer.

Thus was born the idea of defending the city with a movable barrier capable of isolating the Venetian lagoon from the sea. An idea that at the time seemed like science fiction, and which a few years later took the name Mose, an acronym for Modulo Sperimentale Elettromeccanico (Experimental Electromechanical Module), but also a biblical reference to Moses, the man who, inspired by the power of God, parted the waters.

The principle was simple and revolutionary at once: to build at the three inlets a series of gates that could rise only in the event of high tide, blocking the sea and protecting the city.

When, in the early 2000s, the construction sites opened, the Mose immediately became a national case. Environmentalists accused it of altering the Venetian lagoon’s balance, experts deemed it an obsolete infrastructure project, and politicians split between supporters and opponents.

The automatic barriers were installed in 2003, yet the Italian water city remained divided. Above all, the costs weighed heavily: €5.5 billion in the initial estimate, rising to over €6 billion by the end of the works. Added to this were the maintenance and infrastructure management costs, with forecasts running into hundreds of millions every decade.

Then came the judicial investigations. In 2014, the Guardia di Finanza’s “Mose” operation uncovered a system of bribes, rigged contracts, and slush funds that engulfed managers, entrepreneurs, and politicians. The Consorzio Venezia Nuova, responsible for the construction, was placed under administration; dozens of people were arrested or investigated. For many, it was the project’s final condemnation. “A monument to waste,” newspapers called it. “A failure,” declared environmentalists.

And yet, despite everything, the Mose carried on. Slowly, amid administrators and revisions, the movable barrier system was completed, tests resumed, and control systems were updated. The State chose not to abandon the project because, in the meantime, Venice continued to sink and the sea to rise.

The Mose is an infrastructural feat without equal: 78 steel movable barriers hinged to the seabed, up to 30 metres long and weighing as much as 350 tonnes each, which normally lie in their housing.

When the tide exceeds 110 centimeters, they are emptied of water and filled with compressed air. In this way, the gates become lighter, rotate, and rise, creating a barrier that closes the inlets and separates the Venetian lagoon from the sea. When the tide recedes, the gates lower again, invisible beneath the water’s surface.

A system as simple in theory as it is complex in practice. The technical challenges were immense, as it was necessary to ensure the strength of the hinges, prevent corrosion, and coordinate the simultaneous lifting of dozens of gates at three different points of the lagoon. Despite the complexities, the engineering design held firm, even against the accusations of those who claimed it “would never work.”

On 12 November 2019, Venice experienced one of its most tragic nights. The high tide reached 187 centimetres, and the city was flooded by the sea. St Mark’s Square was completely submerged, shops destroyed, the Basilica invaded by a murky tide.

Less than a year later, on 3 October 2020, came the trial by fire. A new exceptional tide threatened the city, and for the first time, all the Mose movable barriers were raised. While outside, in the Adriatic, the sea level rose beyond a metre and a half, inside the Venetian lagoon the alleyways remained dry. “A historic day,” the newspapers headlined. “Venice is saved.”

Since then, the Mose has been raised dozens of times. In 2024 alone, it protected Venice on more than thirty occasions, preventing economic damage estimated between 200 and 400 million euros a year. The same tides that once would have paralysed the city now pass unnoticed.

Like the Golden Gate Bridge, which a century ago its detractors deemed impossible to build, the Mose too has faced mistrust, trials, and seemingly insurmountable obstacles.

Both works endured moral and physical storms to come into being. And just as in San Francisco in 1937, so too in Venice in 2020, the day of its inauguration was not merely the opening of an infrastructure project, but the demonstration that the impossible can become necessary. The Venetian Lagoon lives on, suspended above the water, because someone – despite everything – refused to accept the idea that “they’ll never build it.”