So here is this city set not on the main land but placed on 118 small islands connected by 417 bridges over 177 canals. It's supported by tens-of-thousands of long pilings driven deep into the ground under all the buildings to support the massive weight of the structures. Surely there has got to be an easier way to build a city!
So why did these folks decide to build out here on a swamp with nothing around - no trees, no animals to speak of, no rock quarries, no nothing? While there is no perfectly reliable historical records about the founding of Venice, tradition and the available evidence seem to agree that the original population of Venice consisted of refugees (from nearby Roman cities) who were fleeing successive waves of Germanic and Hun invasions. So when an invader would take over the mainland, they fled to the small, swampy islands where the invaders would not follow them. After a few decades when the invaders moved on to greener pastures, they would move back unto the main land until the next group of invaders came along, and then - back they went to the islands.
Gradually the city took hold and grew... and grew... and grew. Until it was at one point the largest city in Europe. It was a major financial and maritime power during the Middle Ages and Renaissance, as well as an important center of commerce—especially silk, grain, and spice, and of art from the 13th century to the end of the 17th. It is considered to have been the first real international financial center, emerging in the 9th century and reaching its greatest prominence in the 14th century. This made Venice a wealthy city throughout most of its history.