Why is Venice built on water?

Venice was built in a lagoon because people on the Italian mainland needed a safer place during invasions. The marshy islands were hard for armies to reach: too broken for roads, awkward for horses, and tricky for large boats. What began as shelter slowly became a city.

To make buildings stand, Venetians drove timber posts deep into the mud, then built platforms and stone bases above them. Underwater wood can last because the usual rotting bacteria need oxygen. So grand churches and homes still rest on an old forest hidden below.