Residents manually drove the piles and sang an ancient song to keep the rhythm.
Any local resident knows that Venice is an inverted forest.
This Italian city, which is 1,604 years old, is built on millions of wooden logs driven into the ground.
Larch, oak, alder, pine, spruce, and elm, ranging from 3.5 meters to less than 1 meter in length, have held up stone palazzos and tall bell towers for centuries, representing a true engineering marvel that utilizes the forces of physics and nature.
In most modern structures, the work of this inverted forest is done by reinforced concrete and steel. But despite their strength, few foundations today could last as long as the Venetian ones.
"Modern concrete or steel piles are designed with a lifespan of 50 years," says Alexander Puzrin, a professor of geomechanics and geosystems engineering at ETH Zurich.
"Of course, they can last longer, but in residential and industrial construction, a lifespan of 50 years is considered standard," he adds.
The Venetian piling construction technique impresses with its geometry, centuries-old durability, and enormous scale.
No one knows how many millions of piles are hidden beneath the city, but there are 14,000 tightly driven wooden supports under the Rialto Bridge, and 10,000 oak piles beneath St. Mark's Basilica, built in 832.
"I was born and raised in Venice," says Caterina Francesca Izzo, a professor of ecological chemistry and cultural heritage preservation at the University of Venice.
"When I was growing up, like everyone else, I knew that under the Venetian buildings were trees from Cadore [a mountainous region near Venice]. But I didn’t know how these piles were installed, how they were counted and driven, and that the battipali (literally translates as 'pile drivers') were very important specialists. They even had their own songs. It’s incredibly interesting from a technical and technological point of view," the professor explains.
The battipali manually drove the piles and sang an ancient song to keep the rhythm. The mesmerizing and repetitive melody with lyrics glorified Venice, its republican glory, Catholic faith, and promised death to the enemies of the time — the Turks.
In Venice, the expression na testa da bater pai (literally — 'head suitable for driving piles') is still used, which jokingly means that a person is slow-witted or not very bright.
The piles were driven as deep as possible, starting from the outer edge of the structure and moving towards the center of the foundation. Typically, there were nine piles per square meter, arranged in a spiral.
Then the tops of the piles were cut off to create a flat surface below sea level. Cross wooden structures were laid on top — either zatteroni (boards) or madieri (beams). For bell towers, beams up to 50 centimeters thick were used. In other buildings, no more than 20, and sometimes even less. The most durable material was considered to be oak, but it was also the most expensive. Later, oak was only used for shipbuilding — it was too valuable to be driven into the mud. On this wooden foundation, workers laid the stones of the building.
Soon the Venetian Republic began to protect its forests to ensure a sufficient supply of wood for construction and shipbuilding.
"Venice invented forestry," explains Nicola Macchioni, research director at the Institute of Bioeconomics at the National Research Council of Italy, referring to the practice of cultivating forests.
"The first official document on forestry in Italy indeed belongs to the Magnificent Community of the Fiemme Valley [to the northwest of Venice] and dates back to 1111. It outlines the rules for using forests without depleting them," Macchioni recounts.
According to him, these conservation methods must have been applied long before they were recorded: "This explains why the Fiemme Valley is still covered with lush spruce forests today." At the same time, countries like England were already facing a shortage of wood by the mid-16th century, he adds.
Venice is not the only city using wooden piles as a foundation, but there are key differences that make it unique.
Amsterdam is another city partially built on wooden piles. Here, as in many other cities in Northern Europe, the piles go deep down to the bedrock and function like long columns or table legs.
"It works if the bedrock is close to the surface," says Thomas Leslie, a professor of architecture at the University of Illinois.
On the shores of Lake Michigan in the U.S., where Leslie works, the bedrock can be as deep as 30 meters.
"Finding such large trees is difficult, isn’t it? There are stories from Chicago in the 1880s when they tried to drive one log on top of another — as you can imagine, it didn’t work. In the end, they realized they could rely on friction with the soil," Leslie recounts.
The principle is based on the idea of strengthening the soil by driving as many piles as possible, which increases the friction between the piles and the soil.
"The genius of it is, — says Leslie, — that you are kind of using physics... The beauty of it is that you are using the fluid properties of the soil to create resistance that holds the buildings."
The technical term for this phenomenon is hydrostatic pressure, which essentially means that the soil 'grabs' the piles if they are tightly driven in large numbers in one place, Leslie says.
Venetian piles indeed work this way — they are too short to reach the bedrock, and instead, they hold the buildings up through friction.
