Ancient stone circles such as Stonehenge and the Callanish Stones have long perplexed archaeologists and captured our collective consciousness. How were they built? What was their purpose? Why were they placed where they were?

Now a startling new finding at a hidden stone circle site located on an island chain off the west coast of mainland Scotland might finally begin to offer us some answers. There, researchers have discovered evidence of a massive lightning strike right at the center of the circle, reports Phys.org.

"Such clear evidence for lightning strikes is extremely rare in the UK and the association with this stone circle is unlikely to be coincidental," said project leader Dr. Richard Bates, of the School of Earth and Environmental Sciences at the University of St. Andrews.

"Whether the lightning at [this site] focused on a tree or rock which is no longer there, or the monument itself attracted strikes, is uncertain. However, this remarkable evidence suggests that the forces of nature could have been intimately linked with everyday life and beliefs of the early farming communities on the island."

Bates is part of the Calanais Virtual Reconstruction Project, an effort to virtually reconstruct what many of these ancient sites might have looked like when they were first built. The video at the top of this article is one such example, depicting the lost stone circle of Na Dromannan.

As part of their surveys, the team has uncovered a number of other lost circles buried beneath the peat, revealing the extent to which this region is dotted with these mysterious ancient structures.

Perhaps their most startling finding, however, has been the stone circle with the lightning strike. Geophysics revealed a massive, star-shaped magnetic anomaly in the center. While it's unclear whether this anomaly was the result of a single, large lighting strike or many smaller strikes on the same spot, chances are that the stone circle was built here because of the lighting-- either to mark the spot, or perhaps to manufacture it.

Further investigation has revealed that the lightning strike (or strikes) hit the spot more than 3,000 years ago, which was before the peat would have buried it. This timing lines up well with when the circles were built.

"The dramatic results of survey ... demonstrate that we have to understand the landscapes that surrounds these ritual monuments and the role that nature and natural events, including lightning, played in creating the rituals and beliefs of people many thousands of years ago," said Professor Vincent Gaffney of the School Archaeological Sciences at the University of Bradford.

The project has also helped to reveal how many of these ancient stone circles are astronomically aligned. It's all part of piecing together why they were built, and what they might have signified to their builders.

"There is much still to find out about the so-called 'satellite' circles of Neolithic Calanais and this provides an important first step. The modelling of Na Dromannan also helps us investigate whether this circle was astronomically aligned," added Dr. Alison Sheridan, Director of Urras nan Tursachan, the Calanais-based charitable trust that partnered with this research.