Built in 142AD on the orders of Emperor Antoninus Pius, the Antonine Wall was a massive symbol of Roman might, intended to keep raiders at bay.

But now the 60km wall is facing a new threat – from pandemic boredom that prompted fed-up Scots to reach for new hobbies in search of buried treasure.

Incidents of illegal metal detecting at the ancient wall are said to have soared during the pandemic, raising concerns that artefacts may have been removed or damaged as hunters scoured the landscape for trinkets.

The trend is thought to have been ignited by the spectacular Galloway hoard, the collection of more than 100 pieces of Viking age gold and silver found in Kirkcudbrightshire by a metal detectorist.

Although it’s thought some incidents of digging for Roman treasure along the wall were the work of new hobbyists unaware of the legal implications, there are also concerns others have been carried out by more experienced hunters.

The Roman wall, which stretches from Old Kilpatrick in the west to Bo’ness in the east, is listed as part of the transnational UNESCO World Heritage Site Frontiers of the Roman Empire.

While large areas are easily accessed and identifiable by their sweeping grassy mounds, there has been relatively little excavation carried out, making it a particularly attractive location for unscrupulous metal detectorists.

However, they are not the only threat to the ancient monument – motorcyclists are also said to have been using stretches of the wall as racetrack obstacles leaving its surface damaged.

Heritage crime specialists have now called for the public to act as their eyes and ears in an effort to halt incidents there and at other protected sites across the country.

Peter McGrath, head of physical security at Historic Environment Scotland (HES), said crimes at its sites across Scotland have spiked since March last year.

He added: “People were being asked not to wander too far away, and all of a sudden they were discovering what was on their own doorstep.

“We have seen an increase in metal detecting, wild camping, fire starting and general vandalism.

“We have found a great deal of amateur interest in metal detecting in locations such as the Antonine Wall, where we found a number of incidents of digging.

“There’s a perhaps bigger group who found metal detecting as a hobby during that period of time who are not aware of the illegal issues, but there are also individuals who know exactly what they are doing.

“The Antonine Wall is a real target for metal detectorists because of lot remains unexplored below the surface.”

He added that the potential damage caused by illegal metal detectorists was “unquantifiable”, with fears artefacts are sold online or disappear into private collections.

“We can see the damage caused by graffiti or stones that have been dislodged by people climbing up monuments, but unless we catch metal detectorists in the act or straight afterwards with artefacts in their possession, we have no idea of the scale of the problem.”

Wild campers pitching at historic sites were also creating a range of problems, while others were congregating at ancient monuments and precious locations to drink, leaving behind litter and human excrement.

“Some people just see a lovely place to camp but putting in tent pegs may disturb artefacts that are below ground level. We have also had people setting a campfire in a ring of standing stones and at graveyards.

“Once you tamper with a historical artefact or place, it’s difficult to put it back the way it was.”

Incidents have ranged from the theft of a 16th century millstone from Aberdour Castle in Fife in March, to reports of digging at the world-famous Callanish Standing Stones in Lewis, and countless episodes of wild camping on historic sites, monuments being used as toilets, along with vandalism, graffiti and anti-social behaviour.

In one recent incident, vandals risked their lives scrawling graffiti on the sea walls of 15th century Broughy Castle in Dundee. The incident left Historic Environment Scotland with a £5000 clean up bill.

There was also an attempt to break-in to Dunnottar Castle near Stonehaven last June, and recent social media images that showed someone climbing the fragile walls of Ardvreck Castle at Loch Assynt.

More recently, a fire pit was created in the grounds of St Bridget’s Kirk at Dalgety Bay, leaving the site scorched, while last week Police Scotland said thieves had damaged a 2m section of wall at the Category A listed Torwood Castle near Larbert. A number of large stones were taken from the ruined 16th century castle wall.

Scotland has 8,000 scheduled monuments, 47,000 listed buildings and 47 protected shipwrecks – making the challenge of protecting them all from potential damage or criminal activities almost impossible.

Heritage crime had been steadily rising in recent years, thought partly to have been fuelled by the ‘Outlander’ effect which inspired soaring interest in Scotland’s historic sites. In one case, stones removed from Culloden battlefield by a US visitor were later posted back after they experienced pangs of guilt.

In 2019, Historic Environment Scotland and Police Scotland were said to be investigating around 100 cases of heritage crime. Now, there are said to be at least five cases and sometimes up to 11 cases every week, with increasing numbers resulting in reports to the Procurator fiscal and potential court hearings.

As a result of rising incidents, the Scottish Heritage Crime Group was launched two years ago to raise awareness of the impact of criminal activities and to encourage information sharing between partners. It includes representatives from HES, Police Scotland, Treasure Trove – which deals with artefacts found during excavations and by the public – local government archaeologists and the Association of Planning Enforcement Officers.

The group’s work has included training police officers in how to better understand the issues created by heritage crimes and how to investigate them.

As a result, several reports are now in the hands of the Procurator fiscal, with two separate cases set to be heard by courts in Argyll and Skye over the coming fortnight.

Cases under investigation include the theft of a medieval bell from St Finan’s Isle in Loch Shiel, Lochaber last summer, and the deliberate damage to a Neolithic burial cairn at Carn Glas, Achvraid.

The maximum fine for damage to a scheduled monument is £50,000 and between six months and two years’ imprisonment.

Inspector Alan Dron, chairman of the Scottish Heritage Crime Group, said the lockdown message to ‘stay local’ had inspired people to explore heritage sites, leading to unintentional crimes, while protests related to the Black Lives Matter campaign had also led to damage at protected sites.

“Some people don’t understand what they are doing, others are digging up sites that are scheduled monuments looking for treasure and hoping to find gold.

“It is amazing what folk will take, there have been stones removed from various places, anything that is old, such as old grates have also disappeared.

“It is happening right across Scotland,” he adds.

“A lot is down to interest and curiosity. At the Antonine Wall, the amount of people who play on it, take motorbikes on it and use metal detectors there, is phenomenal.”