Venice shouldn't exist. In the 5th and 6th centuries, people fleeing the barbarian invasions of the mainland settled on muddy islands in a lagoon, drove millions of wooden piles into the mud and built a city on top. By tradition it was founded on 25 March 421, and for more than a thousand years it was a republic run by an elected duke, the doge, that grew rich trading between Europe and the East and ruled an empire of ports and islands across the Mediterranean. Napoleon ended it on 12 May 1797. The city it left behind is still almost exactly as it was: no cars, no roads, just canals, bridges and around 120 islands.
It's also a city that people worry about. Fewer than 50,000 people now live in the historic center, there are more tourist beds than residents, and on a summer afternoon the walk from Rialto to St Mark's is a slow-moving crowd. But Venice empties out early in the morning and in the evening, and the moment you step a few streets away from the main routes, you're on your own beside a quiet canal. That's why five days is better than one: the day-trippers see the crowds, and you get to see Venice.
This plan gives each day one part of the city. Day one is St Mark's and the Doge's Palace, day two Rialto, its market and its wine bars, day three Dorsoduro and its museums, day four the islands of the northern lagoon, and day five the Jewish Ghetto, Castello and the Arsenale, with a gondola ride at the end. Padua, Verona and the Prosecco hills come after day five. Because of museum closing days, the plan works best if day one is a Monday. For the bigger picture, see our page on Italy.