Land around Hadrian's Wall, a Roman ruin and one of Britain's top tourist attractions, is being damaged by illegal treasure hunters known as "night hawkers," officials said Thursday.
Parts of the 1,900-year-old World Heritage site are being dug up by people armed with metal detectors who are disturbing layers of history underground and could be removing ancient artifacts.
The area has special legal protection as a Scheduled Ancient Monument where it is a crime to use a metal detector without special permission.
Hadrian's Wall runs coast-to-coast for 73 miles (117 kilometers) across countryside in northern England. Now in ruins, the wall was named after the emperor Hadrian.
It was built by the Romans in AD 122-30 to protect England, then part of the Roman Empire, from the Picts, a fierce Celtic tribe living in what is now Scotland.
Mark Harrison, national crime advisor for English Heritage, a public body which maintains historic sites, said the actions of the "night hawkers" amounted to stealing.
"Just as it is against the law to break into someone's house and steal their possessions, so it is illegal to damage land and steal valuable historical artifacts," he added.
"The objects they are stealing belong to the landowner, in this case the National Trust, and the history they are stealing belongs to all of us."
Hadrian's Wall attracts hundreds of thousands of visitors per year.