Venice Island was built on a foundation of tree trunks. 1200 years later, those same trunks still support almost all of central Venice.
The buildings of Venice are constructed on closely spaced wooden piles. Most of these piles are still intact after centuries of submersion. The foundations rest on the piles, and buildings of brick or stone sit above these footings. The piles penetrate a softer layer of sand and mud until they reach a much harder layer of compressed clay.
Submerged by water, in oxygen-poor conditions, wood does not decay as rapidly as on the surface.
Most of these piles were made from trunks of alder trees, a wood noted for its water resistance. The alder came from the westernmost part of today’s Slovenia (resulting in the barren land of the Kras region), in two regions of Croatia, Lika and Gorski kotar (resulting in the barren slopes of Velebit) and south of Montenegro. Leonid Grigoriev has stated that Russian larch was imported to build some of Venice’s foundations. Larch is also used in the production of Venice turpentine.