Yesterday, Guarino Guarini's masterpiece - ironically about to be unveiled in its full splendour after two years of restoration - was reduced to a blackened hulk, its finely coloured stone and marble cracked and tarnished, its rafters entirely burned away and the detail of its stucco decoration melted by the sheer intensity of the heat. While the Roman Catholic world rejoiced at the heroic rescue of the Shroud by two firemen hacking their way through the bullet-proof glass of the case in which it was kept, Italy's art experts were in an altogether darker mood.
"My first thought was that my grandchildren will never see Guarini's cupola," Lorenzo Mondo wrote in the Turin newspaper La Stampa. The architect Vittorio Gregotti commented: "I'm happy they saved the Shroud. I only hope that to do it they did not neglect the magnificent cupola."
Many foreign tourists think of Turin as a city of motor cars and industrial power, unjustly neglecting a city centre of great elegance boasting some of the most harmonious Baroque architecture in Europe. Guarini was arguably the most talented of the handful of great architects at work there in the 17th century, but one whose name is little known outside Italy and seems condemned to obscurity through sheer bad luck.
His prinicpal works outside Italy, the churches of St Mary of Providence in Lisbon and Sainte Anne la Royale in Paris, were both destroyed during the 18th century, while his San Filippo e la Santissima Annunziata in the Sicilian town of Messina was wiped out by an earthquake in 1908. The cupola above the Shroud, which Guarini completed in 1694, was heavily influenced by Borromini's work in Rome, notably the corkscrew-shaped tower of Sant'Ivo alla Sapienza. Its six layers of interlocking stonework climbed up towards a star-shaped gallery at the very top, imbuing a sense of wonder at the chaos far more compelling than the rather dubious claims of holiness for the Shroud.
As not one but two investigations were launched to discover the cause of the fire, officials suggested yesterday that it started not in the cathedral, as first thought, but in the eaves of the Palazzo Reale next door. The palazzo, historically the residence of the Princes of Savoy, antecedents to the Italian monarchy, had played host just a few hours earlier to a special dinner held for the visiting Secretary-General of the United Nations, Kofi Annan.
A fire alarm inside the palazzo went off just before midnight on Friday, alerting the fire brigade which spent the next 15 hours battling to put out the flames. An unknown number of paintings in the palazzo, none of the first order, was destroyed along with furniture and artefacts estimated to be worth tens of millions of pounds. Although the Guarini chapel was wrecked, the main body of the Cathedral escaped with little more than smoke damage.
The Shroud having been carried out inside its elaborate golden box, was taken to the safety of a secret location believed to be a monastery somewhere in Piedmont, the region of which Turin is the capital.
No firm leads were being followed up immediately by investigators, but theories being thrown around included everything from an electrical fault to arson perpetrated by the Mafia. Could the official dinner have caused a power overload, perhaps in the specially installed kitchen which was set up against a wall contiguous with the Guarini chapel?
Could someone with a grudge against the Shroud have set out deliberately to destroy it?
Italy has an unfortunate recent history of fires hitting its artistic heritage, not all of them accidents. In 1991, the opera house in Bari was burned down on the orders, as an investigation established, of local organised crime. Last year, it was the turn of La Fenice in Venice, and here too Mafia involvement has not been ruled out.
As for the restoration prospects, Italy is notoriously slow in that department.
The country does not have Germany's tradition of rebuilding damaged monuments from scratch, preferring to carry out restoration using as many of the original materials as possible. With a million bureaucratic obstacles to overcome, that means in practice that projects take years just to get off the ground.
La Fenice, for example, has remained untouched since the fire was put out more than a year ago.