Archaeologists have raised the alarm over loss and damage caused by nighthawks in the illegal search for treasure along Hadrian's Wall.
More than 50 holes dug by people undertaking illegal metal detecting have been found at the Brunton Turret section of the 1,900-year-old World Heritage Site, government heritage agency Historic England said.
Nighthawks, the term for illegal metal detectorists, have targeted the turret and well-preserved section of wall, which was built by the men of the Twentieth Legion of the Roman Army, in their search for ancient artefacts.
The ruins of the Brunton Turret section are surrounded by further buried archaeological remains from the frontier of the Roman empire, which are very vulnerable to damage from nighthawks, Historic England said.
The discovery is the latest in a spate of nighthawking incidents along the wall, at Corbridge, Housesteads and Steel Rigg, over the last three years.
All the sites are protected as scheduled monuments where using a metal detector without proper authorisation is a criminal offence.
Historic England is calling on visitors to Hadrian's Wall and Tyne Valley residents to report illegal metal detecting which is "causing loss and damage to our shared cultural heritage".
Mike Collins, Historic England's inspector of ancient monuments at Hadrian's Wall, said: "We know that the majority of the metal-detecting community complies with the laws and regulations regarding discovery and recovery of objects from the land.
"But the small number of people who steal artefacts and damage ancient sites are breaking the law and robbing us all of the knowledge and understanding that objects from the past can give us.
"These nighthawks are committing a criminal offence and we'd like everyone's help to ensure they are caught. Together we can protect the precious shared legacy that our archaeological sites hold."
Mark Harrison, head of heritage crime and policing advice for Historic England, said: "Illegal metal detecting is not a victimless crime.
"We may never see or fully understand the objects taken or damaged because they have been removed from their original sites with no care or record as to their history or context."
He added: "Historic England will continue to work with Northumbria Police, the Crown Prosecution Service and the metal detecting community to identify the small criminal minority who are intent on causing loss and damage to our shared cultural heritage and to bring them to justice."