Wooden Foundation of Venice

Venice, Italy is one of the world’s most iconic cities, and most people don't realise that the city is built upon strong wood, rather than metal or stone. The piling (foundation) is made mostly from alder trees, supporting the city that has many waterways flowing around it.

Why use wood?

When Venice was first settled around the 5th century, builders faced an enormous challenge. The soft, marshy ground of the Venetian Lagoon could not support heavy stone buildings on its own. The solution was to import timber, primarily alder, from forests in what is now Croatia and nearby regions. These trees were cut into long poles and hammered vertically into the lagoon bed until they reached more compact layers of clay.

At first glance, wood might seem like an unlikely material for long-term foundations, especially underwater. Normally, submerged wood would rot over time. However, the piles for Venice were driven into anaerobic mud and permanently submerged in water, depriving the wood of oxygen, not allowing the survival of the bacteria and organisms that typically cause wood to decay.

How is it so strong?

Over centuries, the wood underwent a process often compared to fossilisation. Minerals dissolved in the seawater gradually penetrated the timber, replacing organic material and causing the piles to harden. Rather than decaying, the alder piles slowly became denser and more stone-like, forming an incredibly durable foundation. While they are not true fossils, their transformation is similar in principle: organic material preserved and strengthened by mineral deposits.

The next layer above the wooden foundation was a thick platform of stone, distributing the weight of buildings evenly across thousands of piles. This ingenious combination of wood, water, and stone allowed the infrastructure of Venice to stay sturdy and reliable for centuries.

Today, the survival of Venice still depends on these medieval foundations. Although the city faces modern threats such as rising sea levels and erosion, the wooden foundation continues to be resilient, standing as a testament to human ingenuity and the surprising strength of wood when used in the right way.