Archaeologists discovered ancient gold coins in an unexpected location during a recent excavation in Bulgaria.

The five Byzantine coins, which date back to the reign of Justinian the Great, were uncovered by archaeologists digging at a site in the northern Bulgarian village of Debnevo.

The excavation was announced by Dr. Stiliyan Ivanov, an ᴀssociate professor at the National Insтιтute of Archaeology and Museum, on Aug. 27.

The village, which is close to a fifth-century fortress, has been the site of excavation projects for the past five years.

But researchers were stumped when they found the coins in the remains of a 10th-century house.

As Justinian had ruled the Byzantine Empire from 527 to 565 A.D., the currency predated the structure by more than 400 years.

Ivanov told Live Science that medieval builders likely found the coins while they were constructing the 10th-century house.

The house burned down later that century, and archaeologists believe the site was abandoned soon after.

The coins would still have been considered valuable in the 10th century, and the medieval residents likely kept them as heirlooms.

Ivanov told Fox News Digital that he’s “very glad” about the interest in the coins.

Three of the coins are in excellent condition while two others are stuck together.

Archaeologists believe that they likely melted in the fire that destroyed the medieval dwelling.