According to tradition Venice was founded in AD 452. Inhabitants of northern Italian cities took refuge on the lagoon's islands to escape the Teutonic tribes invading Italy during the 5th century. In 697 the Venetians organized a republic under an elected leader known as the doge. The Crusades and the resulting development of trade with Asia led to the establishment of Venice as the greatest commercial center for trade with the East. Venice became a rigid oligarchy by late 1200s. Wars of conquest enabled Venice to acquire neighboring territories, and by the late 1400s, the city-state was the leading maritime power in the Christian world. In 1453 Constantinople fell to the Turks and with it did the Byzantine Empire too cease to exist. While Venice still had its land possessions to the North and West it is from the East that it derived the bulk of its wealth and this door was now closed. In the early part of the 19th century Venice came under the control of Austria after its defeat by the armies of Napoleon. It finally broke free from its Hapsburg masters as part of Garibaldi's united Italy.

Today Venice faces many challenges, including loss of population to other areas and physical damage from flooding, sinkage, air and water pollution, and age. After severe flooding in 1966, an international effort to preserve historic Venice was coordinated by the United Nations Educational, Scientific and Cultural Organization (UNESCO), and many structures were renovated and preserved. Flooding has occurred throughout the history of the city and continues to be a concern but experiments using mechanical barriers may help minimize the damage. The sinkage of buildings and other structures, caused by the drainage of underground aquifers, has been addressed by limits on groundwater usage and the construction of an aqueduct from the nearby Alps.