In October 2015, Osanna, Pompeii’s archeological superintendent, announced that he’d been receiving a number of unexpected parcels. They arrive addressed to the excavation site in Pompeii and the Archeological Museum of Naples, and hold an assortment of stolen fragments. Many are accompanied by letters of apology attesting to the vaguely formed fears of an uneasy conscience. ‘I would like to return this stone,’ one reads, referring to a teardrop of pumice. ‘My boyfriend took it during our holiday to Pompeii in August, and I feel rather wrong about it.’ Others are more specific, attributing illness and misfortune to the stolen pieces of rock. ‘I wish to return this stone to its original place because my husband is taken long ill,’ a Japanese woman explains. ‘Please put it back in the ground.’ Correspondents often admit to returning the items in hope of appeasing the gods of misfortune – ‘I am convinced that these pebbles that I took from Italy bring me bad luck,’ begins a letter from Florida, ‘For this reason, I’m sending them back so I can be free.’ – while others articulate fears of supernatural forces at play. ‘Taken from Pompeii fifteen years ago’, a man from London confesses, returning a small red rock. ‘I return it to you so the curse can be lifted.’

To understand the curse of Pompeii we must look first to Mount Vesuvius, the double-humped volcano in whose foothills the city was founded in the seventh- or sixth-century BC. As Pompeii became famous for its villas, fish soup and cheap brothels, the volcano was feared and worshipped, invested with magical properties because of its twin traits of abundant fertility and destructive power. Frescoes from the era show the ridges of Vesuvius covered in riotous vineyards, and in Roman mythology its genius loci was the serpent, a symbol of virility. The region was referred to as Campania felix, and even today the enriched produce of the foothills, such as the potent Vesuvian tomato, is renowned across Italy. Yet the Ancient Greeks had named these lands the Phlegraean Fields (‘burning fields’), believing the pockmarked plains to be the gateway to Hades. Shrines dedicated to the pre-Roman deity Mephitis, the goddess of bad smells, swamps and blowholes, remained active well into the Christian era, and with good reason: the Phlegraean Fields is a vast volcanic subterritory, and festering beneath ‘the lucky countryside’ is a four-mile-wide sunken volcano.

When Vesuvius erupted in 79 AD, Pompeii’s destruction was total. Despite various omens – minor earthquakes, dry springs, contaminated wells, the odd behaviour of animals – the eruption came as a surprise to the local population, few of whom lived to tell the tale. One of them was the teenaged Pliny the Younger, who later recalled witnessing the first signs of danger:

a cloud which appeared of a very unusual size and shape … I cannot give you a more exact description of its appearance than by likening it to a pine tree, for it shot up to a great height in the form of a very tall trunk, which spread itself out at the top into a sort of branches […] it appeared sometimes bright and sometimes dark and spotted, according as it was either more or less impregnated with earth and cinders.

As the cloud approached, pumice fell like rain and Pliny described terrified citizens scrambling through the streets ‘having pillows tied upon their heads with napkins; and this was their whole defence against the storm of stones that fell round them.’ ‘Night came upon us,’ he writes, ‘not such as we have when the sky is cloudy, or when there is no moon, but that of a room when it is shut up, and all the lights put out.’

The main cause of death was thermal shock, as the city was subsumed by a 900 degree cloud of ash. Rescue missions were set up by Emperor Titus, but the city was beyond salvage. Over the years, ash solidified into a hard crust and new settlements sprung up, drawn to the black fertile soil. Rumours started circulating in the provinces. The disaster, it was whispered, was not an accident but instead a divine intervention. God’s punishment for the vices of Emperor Titus, and vengeance on Pompeii for its wealth, wine and brothels; ‘drink, luxuriate, embrace,’ an inscription reads in the bathhouse of Pompeii, adding prophetically, ‘for time is brief’. One story of a particularly malignant variety held that a troupe of boozy soldiers defecated at a shrine of Jupiter days before the eruption. In other words, they had it coming.

This is the supernatural vengeance feared by apologetic Pompeii tourists returning their stolen trinkets. ‘Since I took this stone from the Villa of Mysteries there has been a period of constant trouble in my family,’ another alarmed woman explains. ‘And my dog died too. I’m sending back the stone so I can return to normal life.’ Even the smallest of accidents are singled out as evidence. ‘My wife picked up this piece of volcanic rock and ever since she removed the piece, she’s had very bad luck,’ an anxious sightseer explains. ‘It started that day when the tour bus left without us. Two days later my wife broke her toe. She is still in pain. Would you please return the rock to its resting place in the ruins? Before something even more serious happens.’

Leaving the municipal offices of Pompeii, Osanna and I make our way through the cobbled streets towards the ruins of the Forum. ‘We find a city that was frozen in mid-action,’ Osanna tells me, ‘a city in which daily life was brought to a sudden stop.’ We pass the House of the Orchard, a villa named after the green forest frescoes that cover its interior walls depicting snake-like trees and dark blue figs. ‘For all its beauty,’ Osanna says as we wind through the ruins, ‘for all its splendour, something bad happened here, and there’s always been a popular narrative about the city’s downfall. Stories of a city touched by fortune but also by doom.’

Pompeii has had two lives: the city that was destroyed, and the city that was recovered. It’s now the ghost of former glory, a stumped ruin of pumice and marble, coated in a rind of dust. What has fascinated and at times troubled Pompeii’s successive archeologists is the window it provides onto daily life in the early afternoon of 24 August, 79 AD Not all the particulars were welcome: a little further east, for example, is the largest of the brothels, called the Lupanar (‘wolf den’). Its walls are scratched with messages that shocked its first excavators. Felix bene futuis, one reads – ‘lucky boys fuck well.’

In 1599, while digging a canal, the Renaissance architect Domenico Fontana uncovered a wall decorated with unique frescoes and inscriptions. Instead of excavating further, he buried the wall under pumice. The po-faced architect unearthed something that has since been concealed by kings and magistrates: ancient pornography. After Fontana’s cover-up, another 150 years passed before Pompeii was again discovered, and later digs revealed a city thrumming with erotic artefacts. They showed the fascinus, an embodiment of the divine phallus worshiped across the Empire, carved above doorways and windows or fashioned into wind chimes to ward off the evil eye. In the brothels and private bedrooms frescoes celebrating different sex positions were later discovered; jokey marble statues of men whose togas barely cover their tented erections were found in excavated gardens. Perhaps most shocking to Fontana’s Renaissance sensibility were the necklaces worn by women strung with terracotta penises, which dangled like teardrop pearls.

For those who wished to look back to Antiquity as an age of dignity and grandeur, Pompeii presented a problem: an essential source of information, but disfigured by salacious and vulgar erotica. To preserve the illusion, Pompeii was cast as the exception rather than the rule: the classical era’s Sodom, a vice-ridden city destroyed by righteous gods.

The city flattens as Osanna and I enter the Forum, and I’m led towards a caged gallery to the left of square, where clusters of visitors gather to look at an exhibition of bodies. The effigies lie on a bed of gravel, some lifting their arms to their faces, others curled into defensive balls. These harrowing death masks were made during nineteenth-century excavations, when an archaeologist noticed cavities in the ash crust which he filled with plaster. The casts revealed the holes to be the husks of entombed bodies. ‘The ash preserved Pompeii like a detailed photograph,’ Osanna explains. ‘We’ve discovered glass jars with fruits still in them, or ovens with loaves of bread inside. And, of course, the bodies.’

Belief in divine fortune and local deities are widespread in contemporary Campania, just as they were in ancient Pompeii. The patron saint of Naples is San Gennaro, a Catholic martyr associated with fortune and the lottery, and followers of Gennaro’s cult bet on his lucky numbers every month. During the first week of May in Naples thousands gather at the cathedral to observe the ‘blood miracle’: a muddy clod of San Gennaro’s blood, preserved in an ornamental magnifying glass, is inspected, turned over and passed between clergymen until it turns to liquid. When the miracle of liquefaction is announced, the audience explodes into relieved applause, because the ritual is understood as oracular. When in 1980 the blood did not melt, an earthquake killed 3,000 people several days later.

Naples is a city that has known earthquakes, plagues and desperate poverty, episodic shocks and slumps: you need a bit of luck to get by. It’s also a city where petty theft and magic are entwined, and where lost wallets and vanishing watches are blamed on the Munaciello, a tiny hooded sprite that lives in tunnels below the city. The volcanic rock on which it was built is soft and yellow and easy to excavate, which accounts for the many catacombs, ambulatories and cellars that are punched through the city’s belly, and which are a gift to the thief. Take the tradition concerning lucky bones: steal a skull from the ossuary of Fontanelle, which is located in the hillside of the Materdei district, and take it home. Adopt it, clean it up, give it back a living name, build it a little house to live in, kiss it and it will grant your wish. This spontaneous cult of devotion emerged in the 1880s and its evidence remains in church doorknobs shaped as skulls, or decorative chains of crossbones cut into archways.

Leaving the Forum, I head towards some of the villas for which Pompeii was renowned. Grandest of all is the House of Menander, so large that it takes up an entire district. During excavations, archaeologists discovered an underground room beneath the villa, and in it a chest containing one hundred pieces of silver. Pompeii has been plagued by theft since the Roman era, when endemic crime was compounded by the fact that those in power had special license to steal: Nero – or so the defamatory stories go – would dress up as a slave and loot his own city at night. Those who lodged official complaints were punished, so victims turned to astrologers for answers, preparing curse tablets with retributions to be enacted by local gods.

Eighteenth-century archaeologists were surprised to find the ruins riddled with tunnels dug by first-century explorers, suggesting the city had been extensively sacked before official excavations began, and thieves continue to target the site. In a dramatic manhunt in April 2003 Italian police chased down a priceless fresco cut from the walls of the House of Chaste Lovers. The Carabinieri set up roadblocks across Naples and eventually managed to recover the artefact, which shows a cockerel pecking a split pomegranate. The fresco is particularly coveted by Pompeii enthusiasts because archaeologists believe the artist may have been at work on the day of the eruption. It was painstakingly restored to the walls of the house, but the fragments that Osanna receives are not so easily replaced. ‘It’s impossible to put them back,’ he told me, ‘Sometimes the letters mention an approximate location, but this site is extensive – forty-five hectares in total. It’s not like you can just fit a piece back into the puzzle.’

When Osanna became Pompeii’s superintendent in 2013, it was at a time of new optimism for the site, which had finally received a large injection of funding: €75m from the EU for conservation, and another €30m from the Italian government. The preceding years had been marked by a series of small catastrophes. To the great embarrassment of Pompeii’s overseers, the House of Gladiators fell down in 2010 in what local politicians described as ‘a disgrace for the whole of Italy’. Twice in 2012 there were architectural collapses, in the Temple of Jupiter, one of Pompeii’s main attractions, and another in the Villa of the Mysteries.

The new funding has been dedicated to The Grand Pompeii Project, an effort to restore the entire site by 2016. Six ancient residences, including the House of the Wild Boar, have recently reopened, and the site has been armed with fences and CCTV. ‘In the past it was possible to take things, but no longer!’ Osanna assured me from behind his desk, his smile confident. But despite his best efforts, the restoration project is behind schedule and thefts have continued. In 2014, a portion of fresco from the House of Neptune went missing, one that depicted the goddess Artemis with her brother Apollo, stolen, according to police, by experts. In the same year, after severe rainfall damaged a number of buildings, a UNESCO inspector warned that the site could collapse entirely unless ‘extreme measures’ were taken. ‘Perhaps this is what has pushed people to return the stolen items,’ Osanna mused. ‘Perhaps they want to make a small contribution to the survival of Pompeii.’

It may be that the impulse to return items is symptomatic of a new collective conscience around stolen antiquities, and part of the wider debate around international repatriation. In recent years, there have been reports of the return of artefacts to museums elsewhere, suggesting a spirit of atonement. In 2005, a pair of Roman ballista stones were left outside a museum in Israel with a note declaring, ‘I stole them twenty years ago, and they have brought me nothing but trouble,’ adding wisely, ‘Do not steal ancient artefacts!’ We might wonder whether the principle extends to artefacts looted by imperial powers, as well as repentant tourists.

The curse of Pompeii might have other socio-political causes and effects. At Naples’ Carnival this spring, I asked a social worker painting effigies for the parade if she knew anything about the curse. ‘In Naples, nothing is coincidence,’ she replied. ‘Good luck and bad luck always have something to do with the Camorra. Crime is dressed up as lore.’ The organized crime syndicate has been already been blamed for sneaking contracts and carrying out shoddy repairs on the site, and with €100m for restoration, concerns around the siphoning of funds have increased. This year, the director general of Pompeii told Italian papers that he’s recruited a system of ‘whistleblowers and spies’ to fend off a Camorra infiltration of the repairs. He calls the project ‘Operation Deep Throat’.

‘The mafia have been stealing stuff from Pompeii for decades,’ another Carnival volunteer speculates as he joins our conversation. ‘Pompeii’s treasures are legendary and they sell on the black market for millions of euros. And if there’s big money to be made, you’ll find the Camorra close by. Everyone knows that priceless artefacts get smuggled from the digs before they’re even logged,’ he goes on, ‘What you see in on display is only be a fragment of what’s been found.’