Hadrian’s Wall, the 1,900-year-old fortification built by Roman imperial troops in the second century A.D., stretches for nearly 80 miles across northern Britain, winding its way through some of the country’s most beautiful countryside. Unfortunately, this striking monument has apparently been attracting more than hikers and history buffs. According to a recent warning issued by British heritage experts and police, unauthorized metal detectorists—known as “nighthawks”—have being digging illegally at several sites along Hadrian’s Wall, presumably in search of Roman-era jewelry, coins and other long-buried items.

By the time Emperor Hadrian—an experienced military commander and protégé of the previous emperor, Trajan—began his reign in A.D. 117, the Roman Empire had achieved its largest expanse, encompassing some 5 million square kilometers and 70 million people, or about 20 percent of the world’s population. Hadrian would spend more than half his reign traveling throughout the empire, building temples, libraries and other monuments wherever he went. A lover of architecture, Hadrian also commissioned two of the most important surviving buildings in Rome: the Castel Sant’Angelo, overlooking the Tiber River and originally built as his mausoleum, and the Pantheon, which at 142 feet in diameter remains the largest unreinforced concrete dome ever constructed.

In A.D. 122, Hadrian traveled to Roman Britain, where he is believed to have stayed for several months. According to a biography written two centuries after his death, while he was in Britain Hadrian ordered the construction of a massive wall separating the Romans and their subjects from barbarian invaders from the north. Measuring 15 feet high and 10 feet thick, Hadrian’s Wall stretched from coast to coast across northern Britain, a distance of around 73 miles. Initial construction took six years, and the wall was further expanded and improved in later years.

Upon Hadrian’s death in A.D. 138, his successor Antoninus Pius decided to extend Roman rule northward by building a new wall in Scotland, but within two decades the so-called Antonine Wall would be abandoned in favor of Hadrian’s fortification. In the second and third centuries, during the Roman heyday, some 15,000 troops and engineers lined the wall. Combined with another 15,000 to 18,000 elsewhere in Britain, this made up one of the largest imperial forces outside of Rome. Hadrian’s Wall continued in use until nearly the end of Roman rule in Britain, circa A.D. 410. UNESCO designated Hadrian’s Wall as a World Heritage Site in 1987, honoring it along with the ancient Roman border in Germany as a site called the Frontiers of the Roman Empire.

One of many illegal excavations along Hadrian's Wall (Credit: English Heritage)
One of many illegal excavations along Hadrian's Wall (Credit: English Heritage)

According to English Heritage and the National Trust, two organizations charged with protecting Britain’s historic sites, that all-important heritage is now under attack. The organizations joined the Northumberland National Park Authority and Northumberland police this week in issuing a warning against “nighthawking,” or the unregulated use of metal detectors, which they say has recently occurred at several sites along Hadrian’s Wall. Experts investigating the illegal digs found that grass had been pulled up and soil raked through, presumably in search of objects that might have been buried there in Roman times.

The authorities believe the spike in so-called “heritage crime” in Britain coincides with an increased number of amateur metal detectorists that occurred in the wake of such publicized finds as the Staffordshire Hoard, a cache of more than 3,500 pieces of Anglo-Saxon gold found scattered over a field near Hammerwich, England, in 2009. As the sites near Hadrian’s Wall are legally protected, it is a criminal offense to use metal detecting equipment without obtaining authorization from English Heritage. As Mark Harrison, the organization’s national crime advisor, told the Telegraph: “The practice of nighthawking, particularly from such important sites as Hadrian’s Wall, is an issue that we take very seriously….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.”

English Heritage and the National Trust are currently working with the Northumberland National Park Authority and the police to identify the perpetrators, who may face stiff penalties for their actions. In 2013, two men were given one-year prison sentences (suspended for two years) and forced to do community service and pay damages after they used illegal metal detectors to remove Iron Age and medieval-era artifacts from a site in Northamptonshire.