Digging into the orange-brown dirt of southern Norway, archaeologists unearthed several rows of stones carefully arranged in a circle. Intrigued, the researchers continued digging. Stone circle after stone circle reemerged.

They didn’t realize it right away, but they’d just found a 2,200-year-old burial ground for young children.

Archaeologists excavated a site in Østfold in fall 2023 ahead of the expansion of an industrial plant, the Cultural History Museum at the University of Oslo said in a June 24 news release. They expected to find traces of prehistoric life, but what surfaced surprised them.

The team uncovered over 40 circular stone graves. The closely spaced graves measured between about 3 to 6 feet across. Some had large stones in the center.

“They’ve lain here as a secret until we found them,” the excavation’s leader, Guro Fossum, told the Norwegian News Agency. “We uncovered one after another and ended up with 41 round stone formations.”

“There was something special about the whole site,” Fossum told the outlet. “All the graves were so nice and meticulously crafted. Each stone was sourced from a different location and placed precisely in the formation.”

Seen from above, the field of stone graves looks almost like an unfinished cobblestone street.

Underneath the stone circles, archaeologists found pottery fragments and cremated bones. Researchers sent the remains to a laboratory and received surprising news: Almost all of the graves belonged to young children.

Many of the deceased died as infants, but a few died between the ages of 3 and 6, the museum said. The only exceptions were two graves along the other edge of the graveyard belonging to adults.

“There’s a large predominance of babies. Sixteen of them are newborns, and some may not have been full-term pregnancies,” Fossum told ScienceNorway.

The burial ground was used between 800 and 200 B.C., a transition period between the Bronze and Iron Ages when infant mortality was high.

Archaeologists identified the first-of-its-kind site as a 2,200-year-old burial ground for young kids.

“Emotions related to the grief of losing a child make this so powerful and human. It shows that people in the past were not so different from us,” Håkon Reiersen, an archaeologist at the University of Stavanger specializing in the Iron and Viking Ages, told ScienceNorway.

Archaeologists also found several ancient pathways, cooking pits and fireplaces near the burial ground, Fossum told the outlet. The arrangement suggests the graveyard was likely visible to passersby and used as a site of funeral ceremonies.

Finds from the excavation are temporarily on display at the History Museum in Oslo. Archaeologists plan to continue studying the pottery and other artifacts found at the 2,200-year-old burial ground.

Østfold county is in southern Norway, a roughly 70-mile drive southeast from Oslo and along the border with Sweden.