Summary:

- The Altar Stone at Stonehenge, one of the iconic monument's most enigmatic features, has long been a mystery to archaeologists. This massive stone was brought from a quarry over 150 miles away and positioned in a specific orientation within the monument.

- Recent research has revealed that the Altar Stone was likely originally a natural pillar that was carefully selected and transported to the Stonehenge site, rather than being a natural slab that was simply placed there.

- The precise positioning and orientation of the Altar Stone suggests it may have had a ceremonial or astronomical significance for the builders of Stonehenge, adding to the enduring mysteries surrounding this ancient monument.