Altinum

Ancient trading city near the Venetian Lagoon, considered one of Venice's founding predecessor settlements.

Altinum was a prominent city of the Veneti in what is now northeastern Italy, situated near the Venetian Lagoon. Its origins go back to the 8th century BC, and under Roman rule it flourished as a busy trading port with around 20,000 inhabitants. In the 5th century, Attila the Hun's raid sent many residents fleeing to the lagoon islands — laying the groundwork for Venice itself. Final abandonment came around 900 AD due to Magyar invasions. Today the sunken city lies mostly under farmland and has been mapped through aerial archaeology and laser scanning.