A mysterious structure of unknown purpose has been unearthed in the Friuli Venezia Giulia region in northeastern Italy.

The discovery was made during excavations for the fiber optic installation in the town of Torreano, near Udine.

The ancient structure is made of heavy stone slabs that form a rectangle — two long walls and a short back topped by a roof. Archaeologists initially thought it was a burial cist, but an excavation of the structure revealed no evidence of human remains. It only has silty, muddy soil typical of waterways.

The discovery was publicly reported by Ivano Dorbolo’, a scholar of history and archeology, and administrator of the group Valli del Natisone – Ricerche ed indagini archeologiche.