The buildings at the heart of the Ness complex were flanked by two massive stone walls – one to the north-west (dubbed the “Great Wall of Brodgar”) and the other to south-east, between Trenches P and T.
Found in 2007, the “Great Wall” was originally four metres (13ft) thick, with a ditch running along the outer face. In its later life a section adjacent to the north-west-facing entrance was extended to six metres wide (19ft 8in).
It is suspected that the second wall section was added late in the history of the site, perhaps after the original wall had collapsed, or was dismantled.
The addition may have been a later attempt to monumentalise the original construction, or enhance an entrance through the wall.
An exploratory trench over the wall revealed what could be more buildings, and a possible hearth, which would imply that the wall fell out of use, towards the end of the Neolithic and maybe into the Bronze Age, and structures spilled out to the north-west.
The second boundary wall was revealed in 2009. Compared to its northern counterpart, the “Lesser Wall of Brodgar” was a mere two metres thick (6ft 7in) with a flagstone path along its base.
Geophysics scans suggest both walls ran across the width of the Ness appear to curve around at edges of the isthmus. This tied in with the exposed section of the “Great Wall” in Trench J, which curved beautifully at its northern end, and led to the suggestion that the entire Ness of Brodgar complex was a walled precinct.
Excavation has now cast doubt on this.
In 2018, it became clear that although the “Great Wall” curved around the early Structure Five, and had once looked like it continued south-eastwards, it didn’t extend along the shore side. Investigating the clay beneath other huge stones in the wall revealed, as expected, large depressions caused by the weight of the construction.
These were completely absent in the area where it was once thought the wall continued. So it seems the “Great Wall” stopped abruptly. In addition, attempts to find evidence of a connecting at the opposite side of the Ness have been unsuccessful.
The fact the “Great Wall” stands on virgin ground and curls closely around Structure Five, suggests it was also an early element of the Ness complex. Evidence now suggests that both were probably built around the same time, circa 3300 BC.
The “Lesser Wall”, however, was constructed on top of earlier buildings and was, therefore, a later addition to the site.
We can’t tell how high the walls were — they were both robbed of stone in antiquity, probably as a convenient source of stone for later buildings. The “Great Wall” survived to a height of 50cm (1ft 8in) and the “Lesser Wall” 1.7m (5ft 7in).