Venice was built on a marshy lagoon with very soft, waterlogged soil that could not support heavy structures. To create stable foundations, the Venetians drove thousands of long wooden piles—mostly made from water- resistant woods like oak and larch—deep into the soft ground until they reached a harder layer of clay about 5 meters down. These piles were packed closely together, which compressed the surrounding clay and pushed out water, strengthening the ground beneath. The tops of the piles were cut off and covered with wooden planks to spread the load, and then special blocks of dense Istrian stone were placed on top to raise the foundations above the water level. This ingenious method sealed the wood away from oxygen, preventing rot, so many of the original piles are still intact after more than a thousand years

. Once the foundations were secure, buildings were constructed using brick and stone rather than wood to reduce fire risk. The buildings were kept relatively light and low (no more than three stories), with flexible lime mortar and criss-cross patterned inner walls that could flex slightly as the ground shifted. Heavier facade walls with large windows were anchored to the foundations with iron rods to keep the structures stable

. Venice grew by expanding and connecting hundreds of small islands through canals and bridges, initially relying on boats for transportation. The city also engineered a system to collect fresh rainwater in large squares, as the surrounding lagoon water was salty and undrinkable

. This combination of wooden pile foundations, stone and brick construction, and innovative urban planning allowed Venice to thrive on a challenging, watery environment, creating one of the most remarkable feats of medieval engineering in history