It is a mystery which has intrigued archaeologists for centuries: did the huge Neolithic stones which make up Stonehenge form a complete circle?
Now the puzzle has been answered after the dry summer revealed the faint outline of the missing megaliths.
Usually the ground is watered by stewards, to keep the earth moist and the grass healthy.
But this year, the hose they used was too short to reach the whole site. By chance, the incomplete section of the inner stone circle was left to dry out.
When archaeological features have been buried in the ground for a long time, they affect the rate that grass grows above them, even long after they have disappeared. Read more.