Archaeologists found "the most important discovery at the world famous site for 50 years"

The second henge, which is thought to be a ceremonial monument, is about 900m from the ancient stones on Salisbury Plain in Wiltshire. From above the discovery looks like any green field, but using ground-penetrating radar, experts say below the turf lies a circular ditch containing 22 holes from wooden posts that have long rotted away.

Inside the circle are the remains of a burial barrow, which appeared much later and may have been excavated in the early 1900s. The 'wooden Stonehenge' was uncovered just two weeks into a three-year project, led by the University of Birmingham and the Ludwig Boltzmann Institute in Austria. Its aim is to map the area around the World Heritage Site for signs of villages or any other structures.

Professor Vince Gaffney, from the university, said: "It will completely change the way we think about the landscape around Stonehenge. "People have tended to think that as Stonehenge reached its peak, it was the paramount monument, existing in splendid isolation.

"This discovery is completely new and extremely important in how we understand Stonehenge and its landscape."

It appears to have been built on the same orientation as the world-renowned monument, and has entrances to the north east and south west. Prof Gaffney added: "To put this in context, we haven't found a major ceremonial site of this type, or of this significance, for probably 50 years or more within the area of Stonehenge.

"The presumption was this was just an empty field - now we have got a major ceremonial monument, looking at Stonehenge."

English Heritage archaeologist Amanda Chadburn said it was part of a growing body of evidence which showed how important summer and winter solstices were to the people who built Stonehenge some 4,500 years ago.

"The discovery is all the more remarkable, given how much research there has been in the vicinity of Stonehenge," she added.


/Sky News/