The theatre, which was undergoing the last stages of an expensive restoration, caught fire just after 9pm on Monday night. Within half an hour the roof had collapsed and 150ft flames were shooting up into the night sky.
Firefighters managed to save the 18th-century facade and outside walls but could only watch as the stage, stalls and ornate boxes vanished into a smog of thick black fumes.
However, city officials have launched an international appeal for funds to rebuild La Fenice, whose name - literally "The Phoenix" - bears testimony to its fire-ridden history. The Italian government pledged pounds 8m, and the European Union a further pounds 80,000.
Among the many musical figures to express their grief was the Italian tenor Pavarotti, who offered to organise a charity concert to help cover an estimated pounds 200m worth of damage. "The entire world of opera feels like an orphan after such a loss," he said.
The American "Save Venice" committee pledged proceeds from its annual masked ball, expected to be hundreds of thousands of dollars.
A senior prosecutor, Felice Casson, was put in charge of an investigation into the fire. City officials appeared to rule out foul play, instead pointing to an electrical fault.
An environment ministry expert, Giampiero Zucchetta, said it was a miracle the whole area around La Fenice, barely 10 minutes' walk west from St Mark's Square, did not go up in flames. "Venice is like a tinderbox ... with little stone building and lots of wood," he said.
Nearly 200 firefighters were hampered by the narrow streets and because the canals around the theatre had been drained for cleaning.
The 1,500-seat theatre, first built in 1792 by the neo-classical architect Gianantonio Selva, was called La Fenice because it replaced a baroque palace lost to fire. It became famous both for its fine architecture and the virtuosity of its bel canto singers, and counted Napoleon among its fans.
It burned down in 1835 and had to be rebuilt from scratch by Selva's pupils. The new theatre premiered many of Verdi's operas and, in the run- up to Italian unification, became a symbol of resistance to the occupying Austrian army. The modern La Fenice had also been a symbol, as one of the few dynamic cultural centres left in a dying city.
Prominent cultural figures demanded yesterday that the theatre be rebuilt as it was, although the architect Paolo Portoghesi pleaded for the 1792 rather than the 1830s model. The latter, he said, was a "horrendous confection" that had betrayed the original with fake baroque and rococo.Reuse content