How old is venice?

Question

Why did they build it??

Answer 1

Italy was supposedly founded on St Mark's Day (25 April) in 421 AD which would make it over 1586 years old. People moved onto the islands to avoid the barbarian invasions that were happening at the time.

There's an outline of Venice's history here: http://www.veniceword.com/vehistory.html

Answer 2

It wasn't built... it was settled and then built up. Some of the canals existed and many islands where already present. With the invasions from the north the people living out side of the lagoon area (terra firma) began to populate it - the moved towards the it was difficult for the barbarians to invade and ultimately easier to defend.