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ITALY - Police sealed off one of the grandest houses in the ancient city of Pompeii yesterday after a tall column was found smashed. Officials at the site fear the destruction is a sign that Mafia gangs are trying to intimidate them.

Pompeii is Italy's most popular tourist destination, drawing 2.5 million visitors every year. And the house of Obellio Firmo is one of its most important. The villa's owner was a leading figure in the city's political life: at his funeral - before the fatal eruption of AD 79 - 10kg of incense was burned, at vast expense.

The column stood in the villa's garden. No one yet knows exactly how or why it toppled over. The House of Obellio Firmo is being restored, and a high scaffolding next to the column was also found on its side: possibly wind or vandals caused the scaffolding to smash into the column.

But the superintendent of the site, Pietro Giovanni Guzzo, does not believe the damage was simple vandalism. "It's an act of intimidation. It's an attack against a process of transparency and legality. But we won't be stopped, we won't allow them to intimidate us."

Both Pompeii and Herculaneum, the other ancient city destroyed in the same eruption, are in an area where the Camorra, the Mafia of Naples, are a constant menace. There have been dozens of attacks and murders in Naples in recent months as rival gangs vie for control of the cocaine trade.

Sites like Pompeii and Herculaneum, which earn millions every year from the tourist trade, are hugely tempting for the gangs. They extort protection money from restaurants, hotels and other tourist facilities outside the city's gates, but are not beyond trying to get a slice of the action inside.

In 2004 a fake bomb was placed in a Pompei brothel; the following year, 13 people were arrested on suspicion of trying to force the management of the ruins to buy coffee from a single source, at an extortionate price. The price of defiance can be high. During a campaign to elect city councillors in 2004, a candidate, Carlo Cirillo, went missing. Two days later his body was found, missing its head.