EVEN in an area as archaeologically rich as Orkney, it is being hailed as the find of a lifetime.
Experts have unearthed a Neolithic "cathedral" – a massive building of a kind never before seen in Britain – which has left them in awe of its scale and workmanship.
At 82ft long and 65ft wide, it stands between two of Orkney's most famous Neolithic landmarks, the Ring of Brodgar and the Stones of Stenness.
While impressive in their own right, they would have been dwarfed by the monumental building now uncovered and, in comparison, may have been peripheral features in the islands' Stone Age landscape.
Investigative work has been continuing at the Ness of Brodgar since 2003 and the site – which dates back nearly 5,000 years – is slowly giving up more of its secrets.
Nick Card, from the Orkney Research Centre for Archaeology, who is leading the dig, said the building was effectively a cathedral for the north of Scotland.
He said: "It's spectacular. There were hints at the end of last season that we had a quite enormous building here and now we are able to define it more."
The shape and size of the building are clearly visible, with the walls still standing to a height of more than three feet.
Far taller when built, they are 16 feet thick and surround a cross-shaped inner sanctum where the 40-strong excavation team have found examples of art and furniture created from stone.
The building was surrounded by a paved outer passage. The archaeologists believe this could have formed a labyrinth that would have led people through darkness to the chamber at the heart of the building.
The team has also discovered that a standing stone split by a hole shaped like an hourglass was incorporated into the structure, something never seen before in buildings from the period.
Mr Card said: "This is architecture on a monumental scale and the result is the largest structure of its kind anywhere in the north of Britain. It's one of those finds of a lifetime."
The building may have served as some kind of temple, perhaps playing an important role on the journey from life to death in the beliefs of the people of the time.
It was buried under a large natural mound at the tip of the Brodgar peninsula, a huge archaeological site where last year the team unearthed a four-metre-wide wall made of massive stone boulders.
The Great Wall of Brodgar, as its been dubbed, appears to go right across the peninsula and seems to separate the land of the living from the realm of the spirits at the Ring of Brodgar.
Other buildings, over 50ft long and 30ft wide, have also been discovered.
Mr Card said: "It all forms part of this huge, interconnected ritual landscape. If you found somewhere similar in, say, the Middle East, you would be thinking in terms of a temple precinct."
Dr Colin Richards, a leading expert on the period, said the building would have stood at the heart of Neolithic Orkney.
"A structure of this nature would have been renowned right across the north of Scotland – and is unprecedented anywhere in Britain."