Decebalus treasure
The Decebalus treasure was a 2nd-century hoard of precious metal objects, supposedly concealed by Decebalus beneath a watercourse in the ancient kingdom of Dacia. It features in the historical work of Cassius Dio, who claims that the Roman Empire seized the treasure after a captive Dacian nobleman revealed its hiding place.
Story
During the Second Dacian War, many Dacian nobles surrendered or were caught. One of them, Bicilis, disclosed the location of a treasure, supposedly buried at the bottom of a river.
"The treasures of Decebalus were also discovered, though hidden beneath the river Sargetia, which ran past his palace. With the help of some captives Decebalus had diverted the course of the river, made an excavation in its bed, and into the cavity had thrown a large amount of silver and gold and other objects of great value that could stand a certain amount of moisture; then he had heaped stones over them and piled on earth, afterwards bringing the river back into his course. He also had caused the same captives to deposit his robes and other articles of a like nature in caves, and after accomplishing this had made away with them to prevent them from disclosing anything. But Bicilis, a companion of his who knew what had been done, was seized and gave information about these things."
According to the story, the Dacian king Decebalus used Roman prisoners to deviate the course of the Sargetia river and buried a treasure at the bottom. He buried "so much silver and gold and some other artefacts who can survive moisture", after which the river was returned to its original course. The rest of the treasure was deposited in surrounding caves, and the Roman prisoners were slaughtered.