Do not lose the visit of Venice Lagoon recognized as an Unesco world heritage site for its unique ecosystem.
It’s an ancient site which has about 6000 years and that over the centuries has been amended several transformations that brought it to the current landscape.
You can go by boat its 550 km2  dipping yourself in its typical “Barena”, between canals and “casoni” and along its islands from north to south, discovering its history and typical features.