An amateur archaeologist working with a metal detector has uncovered 934 Roman silver denarii in a field in Wesseling, western Germany — the largest collection of coins from the era of the emperor Hadrian ever found in the country, according to the LVR Office for the Preservation of Archaeological Monuments in the Rhineland.

The detectorist, Oliver Riedl, made the discovery last year when his device would not stop beeping. He called the authorities, and a team of experts began digging immediately.

The hoard weighs 6.8 pounds and was likely buried deliberately in the second half of the second century CE, the LVR office said.

"Of course, we can only speculate about the motives, but it's very likely that someone wanted to keep this money safe. After all, banks didn't exist back then," Erich Classen, a state archaeologist and director of the office, told ABC News.

Why the treasure was never recovered remains unclear. "Perhaps the owner died before that could happen, without being able to pass on the knowledge about the coins," Classen said.

Who buried the silver is equally uncertain. Rahel Otte, a research associate at the archaeological office, offered a sense of the hoard's scale: "At that time, an ordinary soldier in the legion earned 300 denarii a year. However, about half of that was withheld for food and equipment. A legionary would therefore have had to save all of his disposable income for about six years to amass the Wesseling hoard."

The find site sits in a region shaped by Roman expansion. Between 39 BCE and 459 CE, under General Marcus Vipsanius Agrippa, the Romans extended the empire's border along the Rhine River, establishing a military outpost that later grew into Colonia Agrippina — present-day Cologne.

The treasure is now on public display at the nearby LVR-LandesMuseum Bonn, where visitors can examine the largest surviving coin assemblage of its period found in Germany.