The Glass Barriers Saving Venice’s 900-Year-Old Church From Flooding

In November 2019, Venice experienced one of its worst flooding in decades. As the acqua alta sirens wailed, the murky Adriatic sea swelled into the city, rising far higher than forecasters had predicted.

In St Mark’s Basilica, Venice’s iconic 900-year-old church, the salty water caused irreparable damage. It seeped into the stones, leaving behind salt crystals that cracked and crumbled ancient columns. The water was also absorbed into the walls causing precious mosaics to fall off.

What is the lowest point in Venice?

Now, the MOSE system of yellow parapets that rise up and block flood waters is in use, preventing another apocalyptic flood like in 2019. But the barriers are only raised when a high tide of 130 centimeters or more is predicted.

The atrium of the fragile church is the lowest point in Venice, lying at just 65 centimeters above sea level. This means that thus far, it has remained vulnerable to frequent flooding exacerbated by climate change and rising sea levels.

Protecting an ancient church from flooding

In 2021, authorities in Venice decided additional protection was necessary to save the ancient monument from watery destruction. A barrier would be built around the perimeter of the Basilica.

The design underwent several modifications to ensure the walls would not compromise the architectural splendor of the church.

After getting snarled up in bureaucratic delays, the barriers are finally in position. Surrounding the pale pink and cream marble exterior are glass panels around a meter high, sunk into the pavement.

They do not impose much of an eyesore and they have proved miraculously effective in halting the damaging flood waters.

Glass barriers are saving St Mark’s Basilica

In early December, several moderately high tides hit the city. They were not sufficiently dangerous to trigger the MOSE flood barriers, so St Mark’s Square was covered by a low layer of water.

St Mark’s Basilica, however, remained dry. “Let’s hope that, from now on, there are no more high waters that will touch the base of the basilica,” said Mario Piana, chief architect of the church.