Glass barriers keep Venice’s iconic St Mark’s Basilica dry during floods

While the Basilica was built on what was one of the city’s highest points at the time, it now sits much lower due to subsidence and rising sea levels

Tourists and residents walk on catwalks during a sea tide of around 97 centimeters (38.18 inches) to cross a flooded St. Mark's Square in Venice (Domenico Stinellis/AP)

It’s a simple solution, but one that may keep the marble columns and valuable mosaics of Venice’s iconic St. Mark’s Basilica safe from seawater-induced erosion: A set of glass barriers installed around the 900-year-old church has kept its floors dry during frequent high tides.

Even after it evaporates, water leaves behind salt crystals that corrode the marble bases of the columns and the floor mosaics, said Mario Piana, the architect and restoration expert in charge of St. Mark’s.

The new barriers are made of glass mounted on a base of armored concrete that is buried below the pavement of the famous St Mark's square to resist the force of surging water. Piana said the system could keep out up to 1.10 meters (3 feet, 6 inches) of water in the square, equivalent to a tide of 1.90 meters (6.2 feet) above sea level.