
The city is divided into the six traditional districts (sestieri) of Cannaregio, San Polo, Dorsoduro (including the Giudecca), Santa Croce, San Marco and Castello (including San Pietro di Castello and Santa Elena).
The buildings of Venice are constructed on closely spaced wood piles which penetrate alternating layers of clay and sand. The buildings are often threatened by flood tides pushing in from the Adriatic between autumn and early spring. Six hundred years ago, Venetians protected themselves from land-based attacks by diverting all the major rivers flowing into the lagoon and thus preventing sediment from filling the area around the city.
During the 20th century, when many artesian wells were sunk into the periphery of the lagoon to draw water for local industry, Venice began to subside. This sinking process has slowed markedly since artesian wells were banned in the 1960s. However, the city is still threatened by more frequent low-level floods (so-called Acqua alta, "high water"). In many old houses the ground floor is unoccupied due to the periodic floods, but people continue to live and work in the upper stories.
Venice is also famous world-wide for its unique Carnival, and with its lagoon is a UNESCO World Heritage Site.
The city was founded by refugees into the marshes of the Po estuary following the invasion of northern Italy by the Lombards in 568 AD. In the mid-8th century, the Venetians remained subject to the Byzantine Empire, and as Byzantine power waned, however, the city obtained autonomy and eventual independence. Venice was a city state (an Italian thalassocracy or Repubblica Marinara, the other three being Genoa, Pisa, and Amalfi). Its strategic position at head of the Adriatic made Venetian naval and commercial power almost invulnerable.
The Republic of Venice seized the eastern shores of the Adriatic before 1200, mostly for commercial reasons, because pirates were a menace to trade. The Doge already carried the titles Duke of Dalmatia and Duke of Istria. Later mainland possessions, which extended across Lake Garda as far west as the Adda River, were known as "Terrafirma", and were acquired partly to guarantee Alpine trade routes, and partly to ensure the supply of mainland wheat, on which the city depended. In building its maritime commercial empire, the Republic acquired control of most of the islands in the Aegean, including Cyprus and Crete, and became a major broker in the Near East.
Venice became an imperial power following the Fourth Crusade, which (with Venetian aid) seized Constantinople in 1204 and established the Latin Empire. Considerable plunder was brought back to Venice, including the Winged Lion of St. Mark, symbol of Venice. Only Venetian ships could efficiently transport the men, supplies, and (especially) war horses.
Venice remained a republic throughout its independent period and politics and the military were kept completely separate. War was regarded as a continuation of commerce. The chief executive was the Doge (duke), who, theoretically, held his elective office for life. In practice, a number of Doges were forced by pressure from their oligarchical peers to resign the office and retire into monastic seclusion.
It was during the "Settecento" that Venice became perhaps the most elegant and refined city in Europe, greatly influencing art, architecture, and literature. Napoleon was seen as something of a liberator by the city's Jewish population. He removed the gates of the Ghetto and ended the restrictions on when and where Jews could live and travel in the city.
After 1070 years, the Republic lost its independence on May 12, 1797 to Napoleon Bonaparte, who delivered the city to the Austrian Kingdom with the Treaty of Campo Formio on October 12 1797. In 1866, along with the rest of Veneto, Venice became part of Italy. After 1797 the city hadfallen into a serious decline, with many of the old palaces and other buildings abandoned and falling into disrepair, although the Lido became a popular beach resort in the late 19th century.