The attacks appear to fit a pattern. The blasts which wrecked two churches in Rome and an art gallery in Milan were almost identical in style and execution to the car bomb which devastated part of the Uffizi gallery and Accademia dei Georgofili in Florence in May. Officials fear that they are witnessing a carefully co-ordinated campaign of terror designed to strike at some of the most potent symbols of Italy's heritage.
And after Florence and Rome, what more obvious target than Venice? The city has been put under protective siege: guards at musuems are searching all visitors. Roadblocks have been set up on approaches to the city and heavily armed police are patrolling Marco Polo airport and the city's railway station.
But the nub of the problem is Italy's wealth of antiquities. 'Where do you start? Are you going to throw a cordon around all the ancient sites, churches, museums and galleries of Italy?' said an exasperated carabiniere, as his men fended off curious tourists at the site of San Giorgio in Velabro yesterday. 'And even if we do put all our men into that, who will guard the judges and the politicians?'
For San Giorgio, described by guide books as a 'Romanesque jewel', it is an academic point now. All that remains of its portico are a couple of stone columns leaning at crazy angles. Experts have been unable to enter the church to determine the full extent of damage because the building is unsound: massive wooden beams have hurriedly been brought in to shore up the 12th-century facade. At St John Lateran the damage is less obvious. But great chunks of fresco have been blasted out of the underside of the 16th-century loggia. The structure is thought to be unstable.