How Venice Was Built?
venicebyvenetians.com, Tiny Fox Lab

Venice was not built directly on the surface of the islets, but instead supported by wooden platforms kept together by wooden piles entrenched in the sea bed. Why? Because those emerging flat lands were not sturdy enough to support a building on them. For this reason, under the Venice lagoon there are literally millions of wooden piles.Tiny Fox Lab Facts

Preview photo credit: venicebyvenetians.com
Source: https://www.venicebyvenetians.com/venice-foundations/