Research at Stonehenge is going in circles--literally. And that's a good thing.

A prolonged drought has revealed that the mysterious monument's ancient stones, which currently arc in a semicircle, likely once formed a complete circle. The source of this discovery? A garden hose, used for watering the grounds, that was too short to reach the monument's far side.

While the grounds around Stonehenge are typically lush and green, the monument experienced an unusually dry summer in 2013. As a result, a groundskeeper noticed odd patterns emerging in the scorched grass that seemed to indicate places where stones would be, if the monument were a full circle.