Structure Twenty-Seven

Buried beneath a mound of midden

First encountered in 2015, Structure Twenty-Seven is a very large sub-rectangular building at the southern end of Trench T.

Built directly on natural boulder clay, the structure lay beyond the southern boundary wall and beneath a massive mound of midden to the south-east of Trench P.

2023: Structure Twenty-Seven at the southern end of Trench T.  (📷 Sigurd Towrie)
2023: Structure Twenty-Seven at the southern end of Trench T. (📷 Sigurd Towrie)

Excavation of the mound began in 2013, which, at first, was thought to be nothing more than a monumental pile of rubbish – a highly visible symbol of conspicuous consumption in the Neolithic.

In 2014, however, the stump of an upright stone at its base suggested there might be more to it. The tonnes of deposited ash and domestic refuse were clearly covering something. Structural remains began to appear in 2015, and, as work progressed, the sheer scale of the building was revealed.

Structure Twenty Seven

Although its north-eastern end has not been exposed, Structure Twenty-Seven was approximately 17 metres long by 11 metres wide, with walls over two metres thick.

Unfortunately, most of its south-eastern and south-western walls are gone, extensively robbed for stone after the building went out of use in antiquity.

But despite the denuded state of its remains, it is abundantly clear that great care and skill had gone into Structure Twenty-Seven’s construction.

This was reinforced in 2022 when the surviving north-western exterior wall was exposed.

As the layers of midden and rubble were removed, the quality of the masonry shone through, prompting site director Nick Card to exclaim: “That must surely be the most immaculately constructed and beautiful Neolithic stone wall anywhere!”

The stonework is, quite simply, exquisite. Arguably the finest masonry uncovered at the Ness site, the wall was formed by regular courses of perfectly fitted stone, the precision of their placement unsurpassed.

In addition, the Neolithic builders also incorporated a deliberate, but very subtle, curve into the length of the wall.  The outer face was also supported on massive projecting, or stepped, foundation slabs, some over two metres long.

This impressive masonry was matched on the south-eastern side, where huge paving slabs extended out from, and in places sat on, the stepped foundations. These also formed the capping stones of a drainage system around Structure Twenty-Seven’s exterior and which connected to a drain exiting the interior under the south-western end wall.

This paving extended around the building, with excavation in 2023 revealing more on its north-western and south-western sides.

The remains of a low wall sit at the outer edge of the paving, perhaps not only defining it but holding back the midden deposits that accrued around the building during its lifetime. Like Structure Ten, it seems that Twenty-Seven may have been surrounded by a paved passageway.

In 2023, a sondage – small, deep trench – inserted in Twenty-Seven’s north-eastern corner confirmed that its thick, yellow-clay floor had been laid over a deep, clay platform.

This construction method is akin that previously noted at Maeshowe and Structure Eight at the nearby Barnhouse settlement and confirms that Structure Twenty-Seven was as well-planned as it was beautifully built.

Stone roof and timber!

Cleaned, defined and ready to lift. The Trench T timber. (📷 Sigurd Towrie)
Cleaned, defined and ready to lift. The Trench T timber. (📷 Sigurd Towrie)

Roof tiles among the rubble over the floor deposits, together with the thickness of its walls, suggests that Structure Twenty-Seven had a stone roof like those encountered across the Ness site.

In 2023, excavation inside Twenty-Seven came across more tiles littering the surface of the debris layer overlying the building’s floor. These lay where they fell when the building was deliberately demolished at the end of its life.

Among these tiles, however, was a very surprising discover – Neolithic timber.

Elena defining the extent of the sizeable wooden plank in Structure Twenty-Seven. (📷 Sigurd Towrie)
Elena defining the extent of the sizeable wooden plank in Structure Twenty-Seven. (📷 Sigurd Towrie)

The acidic soil conditions at the Ness means that the preservation of organic material is very poor. Where it does survive reasonably well it is usually in small, localised pockets.

Three timber deposits were found on the same day – two in Twenty-Seven and one in Structure Eight. These, however, were nowhere near as substantial as the wooden post fragments found in the floor of Structure Twelve in 2019. What we had were mere mineralised fragments.

After that initial excitement, who would have believed more wood deposits would be found – much more – in Structure Twenty-Seven and, late in the season, under Structure Ten.

By the end of the 2023 dig we had over 50 fragmented timber samples, not to mention a section of a plank measuring about 60cm long.

That the timber had survived is remarkable and further examination will hopefully reveal the type of wood – is it a species known to grow in Neolithic Orkney or recovered driftwood?

The bulk of Structure Twenty-Seven’s wood fragments were found among a deposit of clay – the water content around which undoubtedly provided the anaerobic conditions that contributed to their survival.

We suspect they relate to the demolition of the building’s roof and represent the remains of the wooden A-frames that supported the stone tiles.

Early or late?

Given its position beneath a five-metre-deep midden mound, and because it was built on a natural Neolithic ground surface, we originally thought that Structure Twenty-Seven must pre-date most of the other buildings on site.

Plan of Structure Eight at the Barnhouse settlement. (Hill & Richards 2005) [4]
Plan of Structure Eight at the Barnhouse settlement. (Hill & Richards 2005)

But as more of its remains saw the light of the day, doubts began to grow.

The building’s high-quality stonework and stepped foundations are very reminiscent of Structure Ten, which, built around 2900BC, was the last major building on site.

Now, the consensus is that Twenty-Seven is much later in the history of the Ness and probably contemporary with Ten.

Another building in the area that is almost identical to Ten is Structure Eight at the Barnhouse settlement.

It was constructed around 3000BC, when occupation of the former village had ceased. It was raised, on a clay platform, at the site of a large, open-air hearth on the periphery of the settlement – an area that had been a focus of activity, including food consumption and the working of Arran pitchstone.

Although it has not been confirmed by excavation, geophysical survey suggests that Structure Twenty-Seven sits in a similarly peripheral location, beyond the limits of the southern boundary wall.

2023: Trench J supervisor Paul Durdin photographs the surviving stonework of Structure Twenty-Seven to create a 3d model.  (📷 Nick Jones)
2023: Trench J supervisor Paul Durdin photographs the surviving stonework of Structure Twenty-Seven to create a 3d model. (📷 Nick Jones)

Stone-clad interior

Schematic of Structure Twenty-Seven's interior based on evidence revealed so far.
Schematic of Structure Twenty-Seven’s interior based on evidence revealed so far.

From its first appearance there was no doubt that Twenty-Seven was beautifully built. The exquisite masonry of its external walls was enhanced in places by peck-dressing and great care (and effort) had gone into its interior.

Access to the building was probably by a short entrance passage, partially defined by orthostats, in its north-eastern end, which led into a rectangular chamber measuring c11m by 7.5m.

Cladding the interior of Structure Twenty-Seven.
Cladding the interior of Structure Twenty-Seven.

This space was defined by five enormous slabs – measuring up to 4.55m in length and looking for all the world like recumbent standing stones – set into the floor parallel to the inner walls.

From the weathering on the upper edges of the prone slabs, it is clear they were not quarried specifically for Structure Twenty-Seven. Instead they were exposed to the elements for some time before incorporated into the building.

Along each side wall, two of the stone slabs were placed, end-to-end – but not exactly in line to mirror the slight external curve of the walls – with another along the base of the south-western end wall.

The huge slabs were sunk into the floor, leaving only around 15cm standing proud. In the gap between them and the prone orthostats and the inner wall large, flat rectangular flagstones were inserted, cladding the internal wall faces.

The effect must have been stunning, lending the interior of Structure Twenty-Seven an appearance unlike any other Neolithic building discovered to date.

At the end of each the prone orthostat “rows”, more stone slabs projected from the wall to create two recesses at each side of the chamber.

The positions of the orthostats at the south-western end suggests that Structure Twenty-Seven may have had corner “buttress” features akin to those found in Maeshowe. [1]

The building has been so badly robbed that the “buttresses” remain hypothetical at present, but their presence would have created an end recess, or cell, giving Twenty-Seven an interior reminiscent of a stalled chambered cairn.

One of the surviving orthostatic dividers – in the north-eastern corner – was incised with the same rectilinear designs found elsewhere on site.

The excavators had noted the slab had unusual, but faint, markings on its surface. Closer examination – and the right light conditions – confirmed there were many incised lines, some forming chevrons and other geometric motifs.

These add weight to the idea that Structure Twenty-Seven is later than we originally thought.

As well as the Neolithic decoration, the stone also had probable “drag marks” relating to its quarrying and transportation.

Some of the geometric designs were on the hidden, back edge of the orthostat. In addition, it was also clear that the slab’s inner edge had a rounded profile.

These discoveries strongly suggest the massive slab had been re-used, probably removed from an earlier building before being incorporated into Twenty-Seven.

Furniture features and a hearth

Against the inner faces of the surviving prone orthostats, excavation in 2023 revealed the remains of stone, box-like features, or cells.

Whether these represent the bases of dismantled furniture features – such as the multiple “dressers” in Structure Five – or perhaps the remnants of bench-like arrangements remains to be seen.

Among several features emerging from Twenty-Seven’s floor in 2023 was a substantial hearth.

Strangely, it was not centrally positioned, as might be expected in a Neolithic building. It may be that the hearth overlies an earlier, central fireplace, but we will have to wait until 2024 to answer that question.

The presence of a hearth, however, does suggest the building was constructed for the “living”.

What was Structure Twenty-Seven?

Although elements of Structure Twenty-Seven’s impressive architecture have become clearer, the question of its role has not.

We have not yet reached the building’s floor, which, we hope, will contain deposits relating to its use. Was it another variant of the monumental “halls” over in Trench P. Or something completely different?

Was it perhaps an Orcadian equivalent of a timber hall recreated in stone? Or could it be like a structure encountered at Howe, Stromness, in the early 1980s and interpreted (questionably?) as a “stalled tomb”?

Only more excavation can reveal the secrets of Structure Twenty-Seven.

The early Neolithic structure (highlighted in red) unearthed at Howe, Stromness, in the 1970s. The presence of a hearth saw the interpretation that it was a stalled cairn questioned. Note its similarities to Structure Twenty-Seven at the Ness of Brodgar.

Decommissioned, buried and robbed

Whatever its role, after it went out of use Twenty-Seven was dismantled and the bulk of its fabric taken away. Its remains were then gradually, and deliberately, buried in midden.

The presence of animal bone spreads suggests this final demolition was a formal decommissioning event, or events, that was accompanied by feasting — perhaps like that previously encountered at Structure Ten.

Sections of revetment walls emerge from the midden outside Structure Twenty-Seven's eastern wall. (Sigurd Towrie)
Sections of revetment walls emerge from the midden outside Structure Twenty-Seven’s eastern wall. (📷 Sigurd Towrie)

After an unknown period, people returned to the buried remains of Structure Twenty-Seven to further scavenge for stone. Digging down through the accumulated midden they reached their goal and removed much of the surviving masonry.

This robbing may have been episodic rather than a single event, suggesting it was not necessarily a spur of the moment thing, but perhaps a co-ordinated operation.

The robbers not only knew what they were looking for – high quality and worked stone – but where to find it. They inserted revetment walls into the overlying midden to hold it back while they dug for, and retrieved, the material they were after.

The entire south-eastern wall is now gone, along with part of the south-western end and the inner face of the north-western wall. The huge prone orthostats in the north-western side were also removed.

Given the extent of the robbing, the recovered stone was presumably for use in another construction. [2]

Because it was sourced from Structure Twenty-Seven, had the stone acquired some special significance? Perhaps considered auspicious to incorporate into a new build?

Or was it just a handy source of building material?

Whatever the case, we don’t know where the robbed stone ended up. Another unexcavated structure on the Ness of Brodgar site? Or one much further afield?

2023: Structure Twenty-Seven. (📷 Jim Rylatt/Scott Pike)


  • [1] Often described in the literature as “buttresses”, they serve no architectural purpose. In fact, their presence was not only unnecessary but may have impacted the stability of Maeshowe.
  • [2] Structure Twenty-Eight incorporated fine flagstone, with a distinctive pink surface, in its build. To date this pinkish flagstone has only been found in Structures Twenty-Eight, Twelve and Twenty-Six and we have no doubt that stone from Twenty-Eight was re-used in Twelve, which was subsequently robbed to build Twenty-Six.
3d model of Structure Twenty-Seven
Excavation over time - Structure Twenty-Seven