NEW evidence has been unearthed suggesting Orkney islanders once built a physical barrier between the land of the living and the spirit world.
Archaeologists are working on a Neolithic settlement, dating back nearly 5,000 years.
Only a small part of the Ness of Brodgar site has been unearthed, but already experts say it has given up fascinating discoveries and is helping them better understand the wider Neolithic complex between the Ring of Brodgar stone circle and the standing stones of Stenness.
It is even suggested that the remains of the unusual buildings recovered at Ness of Brodgar could be as historically significant as the islands' famous Skara Brae village.
The Ness of Brodgar site, which covers more than six acres, has been investigated since 2003 but it is only this year that archaeologists have been able to access such a wide area.
The team from Orkney College and Orkney Archaeological Trust uncovered the buildings over the past few months. Oval and separated into chambers, their construction suggests they were temples. Other areas were used for domestic purposes.
Nick Card, the project manager, said: "In previous years we have had small areas opened, but this year we have opened larger trenches and it is the first time we have been able to get access to these wonderful structures.
"We are finding evidence of domestic structures and also those for ritual and ceremonial use, with refined architecture very regular in layout and reflecting the style of architecture in late Neolithic chambers."
He said the work suggested there were many more structures hidden under the ground: "We are looking at a considerable concentration of prehistoric structures surviving in places up to over half a metre in height."
He said the team has discovered beautifully decorated prehistoric pottery "by the bucketful" and burned animal bones, indicating evidence of feasting. He said: "There are lots of stone tools and also some exotic items like a polished stone mace head, which probably came from the Western Isles or central Scotland, and a kind of volcanic glass that only occurs in Arran.
"The situation in the heart of Neolithic Orkney, bang in between the Ring of Brodgar and the Stones of Stenness, means it is very important. It's really putting these other sites into a wider context."
Mr Card added: "We are hopeful that every aspect of life 5,000 years ago will be clarified by our discoveries. This is not just about Neolithic life in the north of Scotland - it could have ramifications for the study of the Stone Age throughout Britain."
One of the most important finds is the remnants of a large stone wall, five or six metres wide, which is thought to have been about 100 metres long.
Mr Card said: "The site is at the tip of the Brodgar peninsula and separating it from what was happening to the north in the Ring of Brodgar is this monumental wall, beautifully faced on both sides and made of massive stone boulders.
"You wonder that with foundations of that dimension how high it was when it was built. It appears to go right across the peninsula, so the team here now calls it the Great Wall of Brodgar. It's probably a symbolic barrier. It's been suggested the Ring of Brodgar is the realm of the spirits, the world of the dead, and maybe this wall emphasised the difference between that and the land of the living. We had an inkling about it [the wall] last year but only this year its true extent became apparent."
• THE Neolithic, or New Stone Age, existed from 4000BC to 2200BC. Neolithic people relied on hunting and fishing to survive. Material found in Orkney included the bones of cattle, sheep and pigs, alongside those of deer, whales and seals.
Unlike their more nomadic predecessors, the Neolithic farmers began to build permanent settlements and, by using fire and more advanced stone tools like polished stone axes, began the deforestation of large sections of land for the planting of crops.
The small farming communities gradually developed into larger tribes with, it is thought, a ruling class.
The people of the Neolithic era were also the builders of the stone circles, the henges and burial cairns that pepper the landscape of Scotland. However, the exact nature or purpose of these monuments remains a mystery.
The larger groups would have been able to build the major monuments such as Maeshowe and the Ring of Brodgar. Cairns were an essential part of life to the early farmers, with men, women and children of all ages buried within chambered tombs.
It is thought few of these people reached the age of 50 and many died in their thirties.