If you visit the Field Museum in Chicago for its First Kings of Europe exhibit that opens March 31, keep an eye out for a ragged, unassuming sword. It has a special backstory. The Field Museum had thought it was a convincing replica of a Bronze Age sword. Turns out, it’s the real thing.

The sword is around 3,000 years old. The museum acquired the artifact almost a century ago. It was first discovered in the 1930s in the Danube River in Budapest, Hungary. It may have ended up there as part of a ritual for the dead. 

Field Museum scientists with specialties in chemistry and archaeology examined the sword with an X-ray fluorescence detector, a device that can determine what an object is composed of. “When they compared the sword’s chemical makeup to other known Bronze Age swords in Europe, their content of bronze, copper and tin were nearly identical,” the Field Museum said in a statement this week.

Tracing the sword to its rightful place in history was unexpected. “Usually this story goes the other way round. What we think is an original turns out to be a fake,” said Bill Parkinson, curator of anthropology. 

The sword’s authentication happened too late to include it in the Bronze Age section of the First Kings of Europe exhibit, so the museum instead installed it in the main hall as a preview for the show. 

The sword’s story is like something out of Antiques Roadshow, one of those amazing finds that astounds the audience. What, this old thing? We just found it in a river.