A new discovery has upended the accepted backstory of a central feature of Stonhenge, raising more questions about the mysterious origin of this iconic Neolithic site, reports a new study. One of Stonehenge’s most important monoliths, known as the Altar Stone, likely came from a completely different region of Britain than was proposed 100 years ago, according to researchers. The Altar Stone, also known as stone 80, is the largest of the “bluestones” that form the inner circle of Stonehenge, a mysterious 5,000-year-old monument in Wiltshire, England, that served as a ritual site for millenia. Measuring 16-feet-long, the Altar Stone lies in a recumbent position on the ground, giving it the appearance of an altar, though its original purpose remains unknown. For the past century, researchers have assumed that the Altar Stone came from the Old Red Sandstone basin in the Mynydd Preseli region of western Wales that is the source of Stonehenge’s other bluestones. This origin story can be traced to an influential study published in 1923 by the geologist Herbert Henry Thomas, who suggested the bluestones were hauled from Wales across 140 miles to the Stonehenge site.