Venice, built on the water it never quite tamed

Venice exists because the mainland became unsafe. As the Roman order in northern Italy collapsed under successive invasions in the fifth and sixth centuries, people from Aquileia, Padua and the other cities of the Veneto retreated into the lagoon: a maze of mudflats, sandbars and shallow channels that no army with horses or siege engines could easily cross. It was a defensive position first and a city only by accident. Nobody planning a great trading power would have chosen a swamp.

And yet the swamp is why it worked. Venice built its houses and palaces not on the mud itself but on forests of wooden piles, mostly alder, driven down through the silt until they hit a firmer layer of compressed clay. Submerged in water and starved of oxygen, wood does not rot the way it would in the open air; over centuries it can mineralise instead, effectively turning to stone. The city's foundations are, in a very literal sense, still standing on the trees of the mainland forests that supplied them.

A republic that ruled the sea because it had nowhere else to rule

Cut off from easy farmland, Venice turned to trade and never really stopped. By the high Middle Ages the Republic of Venice, known as La Serenissima, controlled a trading empire that reached into the eastern Mediterranean, the Adriatic coast and beyond, moving spices, silk and salt through a lagoon that doubled as the safest harbour in Europe. The wealth built the Doge's Palace, the basilica of San Marco with its looted Byzantine bronze horses, and the merchant houses along the Grand Canal that still define the postcard view.

The Republic lasted until 1797, when Napoleon ended over a thousand years of independence without much of a fight. What he could not end was the geography. Venice remains a city without cars, its streets are canals, and its logistics still run on boats: the rubbish, the post, the ambulances, the groceries. It is the most impractical major city in Europe, and it has never seriously considered becoming a practical one.

The water that built it is still the water to watch

The same lagoon that protected Venice now threatens it. Acqua alta, the seasonal high water that floods St Mark's Square and the low-lying streets, has always happened; what has changed is its frequency, as the city sinks slightly and the sea rises around it. A system of mobile flood barriers, decades in the planning and building, can now be raised across the lagoon's inlets when a serious tide is forecast, holding the Adriatic out long enough to spare the piazza. It is not a permanent fix, and nobody involved in the project claims that it is; it buys the city time, which is roughly what Venice has always needed most.

None of this makes Venice fragile in the way tourists sometimes assume. It has absorbed sixteen centuries of floods, fires, plagues and the loss of its empire, and it is still, unmistakably, Venice. What it asks of a visitor is a little patience with the way the city actually works: you will get lost, the water will occasionally be in the wrong place, and none of that is a flaw in the plan.

Beyond the canals: the Veneto that made Venice rich

Venice's hinterland, the Veneto, is where the Republic's money went once it had been made. Vicenza is essentially an open-air museum of Andrea Palladio, the sixteenth-century architect whose villas and public buildings, built for merchants who wanted a Roman temple to live in, influenced country houses from England to the American South. Verona has a Roman arena still used for opera and a set of medieval streets that Shakespeare, who never visited, made famous anyway. Bassano del Grappa gives its name to the spirit distilled there and has a wooden bridge, also designed by Palladio, that has been rebuilt after floods and wars more times than the town likes to count.

A week that combines Venice with towns like these makes more sense of the city than Venice alone can, because it shows where the wealth on the Grand Canal actually came from, and what the Republic looked like once you left the lagoon behind.

Go in spring or early autumn if you can. Venice in high summer is hot, crowded and short on shade; in April or September it is still recognisably itself, only easier to enjoy.