UK's Stonehenge has buried bigger brother

Stonehenge. Photo / Thinkstock

Archaeologists have discovered that Stonehenge had a huge stone sibling just 3.2km to the northeast.

Using powerful ground-penetrating radar, which can "x-ray" archaeological sites to a depth of up to 4m, investigators from Birmingham and Bradford universities and from the Ludwig Boltzmann Institute in Vienna have discovered a 330m-long line of more than 50 massive stones, buried under part of the bank of Britain's largest prehistoric henge.

"Up till now, we had absolutely no idea that the stones were there," said the co-director of the investigation Professor Vince Gaffney of Birmingham University.

The geophysical evidence suggests that each buried stone is roughly 3m long and 1.5m wide and is positioned horizontally, not vertically, in its earthen matrix.

However, it is conceivable that they originally stood vertically in the ground like other standing stones in Britain. It is thought that they were probably brought to the site shortly before 2500BC.

They seem to have formed the southern arm of a c-shaped ritual "enclosure", the rest of which was made up of an artificially scarped natural elevation in the ground.

The c-shaped enclosure - more than 330m wide and over 400m long - faced directly towards the River Avon. The monument was later converted from a c-shape to a roughly circular enclosure, now known as Durrington Walls - Britain's largest prehistoric henge, roughly 12 times the size of Stonehenge itself.

As a religious complex, it would almost certainly have had a deeply spiritual and ritual connection with the river. But precisely why is a complete mystery, although it is possible that particular stretch of water was regarded as a deity.

The discovery is part of a much wider archaeological investigation into Stonehenge's sacred landscape.

A two-part special BBC Two documentary Operation Stonehenge: What Lies Beneath is set to reveal the details of many of the discoveries.

As well as revealing the previously unknown stones of Durrington Walls, the Anglo-Austrian-led investigation has succeeded in locating more than 60 other previously unknown prehistoric monuments.

Using ground-penetrating radar, magnetometry and other geophysical techniques to peer beneath the landscape's surface, archaeologists have found around 17 other henge-like Neolithic and Bronze Age religious monuments, each between 10m and 30m in diameter. Some may have consisted of circles of large timber posts - wooden equivalents of conventional prehistoric stone circles.

But the archaeologists have also discovered about 20 large and enigmatic ritual pits, each up to 5m across.

They have also discovered more than half a dozen previously unknown Bronze Age burial mounds - and four Iron Age shrines or tombs, as well as half a dozen Bronze Age and Iron Age domestic or livestock enclosures.

In total, around 11.5sq km of buried landscape has been surveyed in an exercise that has taken four years.

Now the archaeologists plan to analyse the new data to work out how all the newly discovered prehistoric monuments related to one another.

Using avatar-based computer models, they are hoping to tease out exactly how Neolithic and Bronze Age people used Stonehenge's landscape.

Initial results suggest that some of the newly discovered shrines and other monuments grew up along processional ways or pilgrimage routes in Stonehenge's sacred landscape.

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