In January father and son team Edward and Michael O’Neill discovered the headwaters of the aqueduct, which was built by the Emperor Trajan, hidden beneath a crumbling 13th century church north of Rome.
A sophisticated example of Roman hydraulic engineering, the aqueduct, known as the Aqua Traiana, was inaugurated in 109AD and carried fresh water 35 miles to the imperial capital.
But since the discovery was publicised, the archeologists claim that the farmer on whose land it stands has begun a crude excavation of the site in the hope of finding valuable Roman treasure.
They claim to have photographic evidence that the owner has burned vegetation around the entrance to the underground grotto, cut down mature fig trees which are holding the fragile structure together with their thick roots and started to dismantle sections of masonry.
“It’s a complete tragedy,” Edward O’Neill told the Daily Telegraph. “He’s doing some kind of treasure hunt.