A team of electrical technicians stumbled on a “secret” medieval tunnel while undertaking a routine dig to relocate a span of underground cable.
The Western Power Distribution contractors had just begun excavation work in Tintern, Monmouthshire, when they made their extraordinary discovery.
The brick tunnel, which stands at around four feet tall, is thought to date back almost 900 years.
The ruins of Tintern Abbey, a Gothic monastery founded in 1131, are near to the valley where the tunnel was found. But the passageway isn’t shown on any ordinance survey maps and it was unknown to local residents and authorities, Western Power Distribution say.
It could take “years” of archeological investigation before more about the “secret” tunnel is known, WPD technician Allyn Gore said.
In the meantime, his team have backfilled the trench they had begun digging and are putting their cables down elsewhere.
Mr Gore, who headed up the dig team, said he had never seen anything as “exciting and impressive as this” during excavations before.
“The tunnel system was tucked away underneath a footpath, running parallel to the Angiddy Brook, and seemed to follow the brook’s route along the valley; it may have been unknowingly walked on for centuries,” he said.
His team alerted Cadw, the Welsh Government’s historic and cultural heritage agency, who were “fascinated by the sheer scale of the tunnel” and thought it could be “linked to iron work ruins previously discovered in the area”, he said.
Archeologists are now working to establish more details about the tunnel.
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