The burning of its opera house is only the latest in a catalogue of disasters to befall Italy's most vulnerable city. The real threat to its existence remains a unique combination of corruption and intransigence. Andrew Gumbel reports
T he blazing inferno that destroyed the opera house of La Fenice in a few short hours on Monday night might not spell the end of Venice as we know it, but such a catastrophe could only have happened in a city already long accustomed to the lingering stench of decay and death. Everything about the fire, and the frantic efforts to contain it, reflects sadly on how fragile a jewel Venice is and how unprepared it is to survive in the modern world.

There were no roads for the fire brigade to speed along once it had been alerted, no fire hydrants on which to hook their hoses, and no easy access to an opera house built like a mini-fortress on its mud-flat foundations. Firefighters could not travel along the nearby canals because they had been drained for dredging work; and actually, even if the canals had still been filled, the sheer quantity of sludge on the bottom would have prevented the fire boats from passing under the low bridges.

Everything about the old city of Venice is enough to make a fire inspector weep: buildings made predominantly of wood, not stone, and packed so tightly together that a fire in one could easily spread across an entire sestiere. Venice may be built on water, but one stroke of bad luck and it could suffer the same fate as London in 1666. "The wind wasn't too strong on Monday night," remarked Gianpiero Zucchetta, who inspects fires in Venice for the Environment Ministry, "but if it had been blowing about like it is today, the flames could have reached the Zattere [sea front] and then it would have been bye-bye, Venice."

Fire is only the latest ogre to raise its head in a city that has been slowly dying at least since the 18th century. Beauty alone has not been enough to protect it from the ravages of time, and it sits on the northern edge of the Adriatic like a half-preserved corpse fussed over by teams of quarrelling embalmers, by turns nostalgic for the past and apprehensive about the future. The canals may shimmer enigmatically in the sunshine, but they also stink of rotting garbage and the sewage that seeps out of the old palazzi.

These days the old city of Venice makes a lucrative but frustrating living from mass tourism, while across the lagoon its monstrous modern suburbs, Marghera and Mestre, play host to the biggest petrochemical complex in Italy. The tanker port, oil refineries and chemical factories might provide much-needed employment to upwards of 15,000 people, but they have also eroded the sea bed with their tanker traffic, causing Venice slowly to sink into the mud, and filled the lagoon with virulent nasties including dioxin and heavy metals. These in turn have spawned a sinister mutant strain of animal and plant life - tens of thousands of sewer rats larger and more resilient even than their formidable counterparts in Rome and Naples, giant mosquitoes that make the tour groups' life hell in the summer months, and putrid clumps of algae that surface periodically to further stultify the damp, fetid air.

To some extent, decay is part of the great attraction of Venice. The poets have been singing hymns to the inexorable decline of the place since Byron, and thanks to Thomas Mann (an author cursed by most Venetians for lumbering them with the image) Venice and death have become inextricably linked in Western cultural consciousness. The attraction does not make the city fathers' job any easier. As the late Italian senator and native Venetian Bruno Visentini once said, the management of decadence is a delicate task.

The notion of "saving" Venice has been around since the great flood of November 1966, which devastated large chunks of the city and seriously threatened its artistic heritage. The Italian government has made repeated pledges of cash and institutional support ever since to preserve the city and protect it from flooding, sinking or rotting to death; Unesco, meanwhile, oversees 24 national committees ,including Britain's Venice in Peril fund, which devote their attention to restoring individual palaces and churches.

Venice in Peril has restored the churches of S Nicolo dei Mendicoli and Madonna dell'Orto (where Tintoretto worshipped and is buried) in their entirety. It has renovated Sansovino's loggetta at the base of the belltower of St Mark's. It has funded the restoration of Palladian facade of S Francesco della Vigna and the gloriously theatrical S Pantalon. It is reviving the outdoor frescoes at Torcello. In fact, since it was founded in 1971, it has completed 18 major, and prestigious, projects. The destruction of the Fenice can only spur it into greater fund-raising activities.

Yet the results of these efforts have been rather less than the sum of their parts. The only truly large-scale project to have seen the light of day was back in the early 1970s, the construction of two new aqueducts to stop Marghera and Mestre draining the lagoon for their water supplies. These certainly put an end to the panic that Venice was sinking, although the subsidence caused by the industrial exploitation of the lagoon has not entirely halted. The deep channels cut to make room for the tankers and other deep-draught vessels coming into Marghera, as well as the rising sea levels caused by the greenhouse effect, have ensured that Venice is still dropping a few millimetres each year into the water.

Most other projects are still making their painfully slow way to realisation. The much-touted Moses flood barrier, a series of underwater modules intended to prevent a repeat of the 1966 floods by blocking off the three entrances to the lagoon, has undergone revision after revision and is currently undergoing a year-long vetting by a committee of international experts nicknamed the Five Sages.

Likewise, some work has gone into preventing the smaller-scale acqua alta, which floods out St Mark's Square several times each year. Proposals include installing one-way valves in the gutters, building walls around certain areas of the city, or placing an insulating sheet beneath the most flood-prone spots.

Every idea has tended to fall victim to political wrangling between idealists concerned exclusively for the architectural fabric of Venice, environmentalists worried that solving one problem can open up a Pandora's boxful of others, and trade unionists keen to protect jobs on the mainland. Furthermore, Venice is considered so precious that every decision is subject to endless committee meetings, approvals and reapprovals. Digging up a street requires 37 signatures from 24 different offices from local through to national level. No wonder nothing ever gets done.

"If we decide to plant a new mooring pole," says Giancarlo Galan, president of the Venice region, "do you know how much time it takes before the crane arrives to put it in place? Six years." In theory, the region has been allocated 1.2 trillion lire to overhaul Venice's water system (including provisions for the fire department), but in fact it has managed to spend less than 10 per cent of its budget because of bureaucratic delays.

For a long time Venice was not helped by its corrupt local council, which now faces prosecution for a long list of misdemeanours including the diversion of funds into illegal party financing. During the 1980s the city was carved up between the now discredited Christian Democrat party and the even more discredited Socialist Party, with Italy's disco-dancing former foreign minister, Gianni De Michelis, acting as unanointed city supremo. Under his direction, Venice gave the go-ahead to a disastrous Pink Floyd concert in 1989, which turned St Mark's Square into a giant latrine and damaged the surrounding buildings through amp vibration. De Michelis also lobbied hard to bring Expo 2000 to Venice with plans to turn the city into a mini- Disneyland; widely suspected of trying to aggrandise himself and not Venice, he was finally forced him to stand down.

Since 1993, Venice's city council has been headed by a prominent local left-wing intellectual, a bearded philosophy professor called Massimo Cacciari, who has restored some discipline to the city exchequer and activated many of the projects on hold since 1966. The lagoon is now being cleaned up and some of the eroded mud channels are being filled; moreover, he has initiated the first canal-dredging operation since the 1950s - a process begun, inauspiciously perhaps, in the Santa Maria del Giglio area around La Fenice but which should eradicate the infamous Venice smell by the year 2010.

Even an active city council can only achieve so much. Venice's biggest tragedy is the steady departure of its inhabitants, of whom there are now no more than 70,000 compared with 170,000 before the War. Living in a predominantly tourist city takes patience and money (try getting a plumber to drive a motor boat up your canal on a Sunday night); the particular skills required in a water-bound city are rapidly waning; and shopping for just about anything other than coloured paper or Murano glass is difficult without a trip to the mainland.

The burning of La Fenice is doubly poignant because the opera house was one of the few dynamic centres left in the city. Even if it is rebuilt in two years, as Mayor Cacciari hopes, there is a feeling in Venice that it, and perhaps life in the city in general, will never be the same. "How brave they were as they combated the fire," said Ferdinando Camon in a wry comment for the Turin paper La Stampa. "Just like doctors over a moribund patient. We all want to thank them, but the patient will die anyway."

There is no doubt, however, that many of the city's suitors love her for, rather than despite, her wrinkles. They will continue to pick up her doctor's bills, while the Venetians and Italian governments continue to bicker.