A group of construction workers fixing water pipes in the Spanish city of Seville made an unexpected underground discovery this week — a stash of ancient Roman coins weighing more than 1,000 lb. and believed to be worth millions of dollars.

The coins were found in 19 amphoras or jars in the town of Tomares near Seville on Wednesday, the Guardian reports. They bear the insignia of Emperors Maximian and Constantine, and are believed to date back to the third and fourth centuries, when the Romans ruled the Iberian Peninsula of which Spain is a part.

“It is a unique collection and there are very few similar cases,” Ana Navarro, head of Seville’s archeology museum, told the Guardian. Navarro declined to give an exact value for the ancient currency, but said they are worth “certainly several million euros.”

[Guardian]

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