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| The broch of Mousa: by kind permission of David Simpson. | 
Mousa
 is a small island off the coast of mainland Shetland with a Norse name.
 The 'a' at the end, as in many British place-names, means 'island.' 
'Mous' means 'mossy.'
The
 'Mousa boat' ferries you across to the moss. It's a nature reserve now,
 and well worth visiting for the birds and seals alone. But what I 
wanted to see -- what I'd wanted to see for years -- was the Broch of 
Mousa. It did not disappoint.
The
 first glimpse of the broch is a striking: a monumental tower, against 
sky and sea, its walls gently curving like those of a modern cooling 
tower.
Amazement only grows from there. 
To consider place-names again, the word ‘broch’ is the same as the ‘borough’ or ‘bury’. It means ‘fortified place’ or ‘castle.’ Archaeologists adopted the Scottish form ‘broch’ as a name for the ‘towers in the north,’ the dry-stone, ancient towers found all over Scotland and only in Scotland.It’s
 impossible to accurately date these mysterious towers though it’s 
broadly agreed that they are ‘Iron Age’ and the oldest may be as much as
 three thousand years old— but Maeshowe, in Orkney, shows that there was a strong tradition of building dry-stone corbelled structures, going back five thousand years. (A
 corbelled roof is where dry-stone slabs are skilfully overlapped to 
form a smooth, inward curving roof sealed with a single cap-stone.)
 
Above,
 the interior of the passage-grave, Maeshowe, on Orkney, showing its 
smooth, inward curving, corbelled ceiling. It is acknowledged as 'the finest Neolithic building surviving in north-west Europe.'
 The main building is estimated to be at least 5000 years old, making it
 older than the pyramids. Its entrance is aligned to the setting sun at 
the midwinter solstice.
The
 immense, upright stone slabs at the corners have no constructive 
purpose at all. They are not holding up the roof or supporting the walls
 as you might think. They were already in place before Maeshowe was 
built. The grave was built around them, as if to preserve or honour 
them. Possibly they were standing stones. Perhaps the remains of another
 house or grave. I don't know about you, but this makes my brain boggle.
Mousa’s broch is the most complete of all brochs, still standing 13m (42/43 feet) high. Its
 twin, the broch of Burraland, which stood on the other side of the 
strait between Mousa and mainland Shetland, was ‘robbed out’ for 
building stone and is now only 2-5 metres (8 feet) high. It's 
sometimes suggested that Mousa's broch was protected from destruction by
 its position on a small island -- even though Mousa was home to 
stone-hungry crofters until the 19th century. 
Mousa’s
 excellent preservation tempts us to take it as a model for all brochs 
but archaeology shows that Mousa is very untypical. It’s quite small, 
underwent considerable alteration in antiquity and, overall, is much 
better built than your average broch. Its superior construction may have
 been its salvation: it was simply harder to dismantle than other 
brochs. Whatever preserved it, there’s no doubt it deserves its status 
as a World Heritage Site.
To give a simple account of the broch’s interior:
 
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| Inside the broch of Mousa: copyright: David Simpson.There
 are no windows in the outer wall and only one entrance, facing the sea.
 This entrance is 1-5 metres (5 ft) high and the passage behind it is 5 
metres (16ft) long. At the end of the passage a ‘bar-hole’ can be seen 
in the wall. This is where a solid wooden 'bar' would have been put in 
place, to prevent the door being opened from outside. Whoever lived -- 
or took shelter -- within these massive walls was keen on some other 
people staying outside. The
 entrance passage opens into a roughly circular space. At its centre is a
 hearth and a stone water-tank, reminiscent of the five thousand year 
old neolithic houses at Orkney’s Skara Brae.  Although
 the outer circumference of Mousa Broch is 15m (45ft), the interior is 
only 6m (19-20ft) in diameter.
Built into the massive base of the broch are three large corbelled 
cells, differing slightly in size. The largest is about 1-5 metres (5ft)
 wide, 4 meters (13ft) long and 3 metres (11 ft) high. The doors into 
these cells are raised above the floor of the broch, perhaps to keep out
 draughts. Each also has a built-in shelf— again, like Skara Brae, where
 the bed-spaces had shelves built into the walls beside them. The
 walls above the cell-doors have gaps or windows constructed into them, 
possibly to lighten the load each lintel has to bear and to allow light 
into the cells. Modern houses can have rooms smaller than these without the storage.  Mousa's
 tower is double-skinned, with a ring of outer wall, a ring of inner 
wall and a gap between them. The outer and inner walls are pinned 
together with slabs of slate.
 In this way ‘galleries’ were formed between the walls. It's possible, 
with some stooping and squeezing, to walk along these galleries to their
 blind ends. At other brochs, at least where enough of these galleries 
remain to judge, it isn't. They are too low and too much stone protrudes
 into them. These galleries are due to Mousa broch's method of construction: the twin walls were built up to a certain height, then slates were used to bridge the gap between them; and then the walls were built higher and 'pinned' again. The galleries weren't intended to be lived in, or to be used as storage -- but all the same, I'd guess that they were so used, at least to some extent. The broch's
 builders used the gap between the walls and the pinning slabs to make 
an interior stair which winds inside the walls right to the top of the 
tower. (The hand-rail is modern.)
 
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 Beyond this, much is conjecture.
For
 instance, the inner wall was constructed with tall rows of gaps, 
(giving ancient Mousa a startlingly modern ‘architectural’ look.) It’s 
often argued that these were to ‘light the stairwell’ and the corbelled cells, which they 
certainly do today because now the tower is roofless. Perhaps it was 
roofed somehow, in the past, and the purpose of the 'gaps' was to reduce
 weight on the walls? 
 
Roofed or Open?
 There
 are endless arguments about what the summit of the broch was originally
 like. The top was somewhat reconstructed -- with guesswork -- in the 
1960s and '80s, so that now you can walk around on top, admiring the 
view. But no one knows for certain what the top of the broch was like when first built.
Some
 argue that there was no walkway and that the broch was always open to 
the weather, as now, allowing the rain and snow to fall down between the
 concentric walls.
Another
 argument insists that the broch was roofed somehow, though no one can quite figure out how. Maybe the gap 
between the walls was turfed or thatched, leaving the courtyard open... 
Maybe the whole top of the broch was covered by a conical thatch, making the broch look like a very tall Iron Age roundhouse.
 
 Stretch!
 The Open-to-the-Sky mob reply that the weight of the supporting timbers, plus 
thatch, pressing
 outward against the walls would make this unlikely. Also, it would make
 the broch's interior impenetrably dark. (True, but many houses in the 
past were windowless and dark. Viking longhouses, for instance. 
Inhabitants spent much of the day outside and, at night, there was fire 
and lamplight.)
It's
 a conundrum. About the roof, I'm neutral but think there must have been
 some kind of platform up the top there. Why go to the enormous effort 
of building a dry-stone tower that may, originally, 
have been more than fifteen metres high (49 ft) , with a stair climbing all the way to the top, if not to stand up there and see further than from ground level?
More Conjecture 
At some point in antiquity, a stone wheelhouse
 was built inside the stone tower. The hearthstone and water tank belong
 to this wheelhouse, as does the wide stone ‘bench’ that runs around the
 inside of the tower. (You can see the 'bench' or wall in the photo of 
the interior above, running around the wall towards the left,) 
The
 builders of the stone wheelhouse continued to use the broch's corbelled
 cells, because they left gaps in their own stone wall, to allow them 
entrance. But they built across the entrance to the broch's stairs and 
galleries, blocking them off. Obviously, they had no love of a sea-view 
or a need to know who was approaching.
It
 was possibly around the time this inner wheelhouse was built that the 
broch’s entrance was altered, making it much larger. This also meant 
breaking through the floor of a corbelled cell built above the entrance.
 (This cell must originally have been entered via the stairs and some 
kind of upper floor. There are also endless arguments about how this 
upper floor may have been built into the broch.)
 
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| Dun Carloway, Lewis: by permission of David Simpson | 
By
 making Mousa's entrance larger, it was also made less defensive 
than 
the entrances of other brochs, such as Dun Carloway on Lewis, where the 
doorway is much smaller and narrower.
Why
 were the brochs built? The theory favoured in the 19th Century was that
 they were defensive ‘castles.’ Hence their name: 'broch, a fortified place.' Then, in the 'Peace and Love' of the 1960s and 70s, it became fashionable to say that they weren’t
 defensive because they couldn’t have withstood a determined attack. No,
 they were merely the prestigious houses of a ruling elite. 
Brochs
 have tall, thick walls, entirely windowless on the outside. Most 
brochs, unlike Mousa, have low narrow doors, that make you stoop double 
to enter. Yet the builders could make corbelled ‘cells’ 3 metres high, 
so the entrances weren’t low for ease of building. They could construct 
windows too, so the outer walls were deliberately made without openings.
 
Behind
 the entrance, brochs have long, low, easily defended passages with 
doors which could be strongly barred. None of this speaks to me of an elite’s 
comfort. It positively screams ‘defensive’.
If a broch couldn’t have withstood a determined attack, neither could the later pele towers of the Borders but no one doubts they were
 defensive. Rather than withstand ‘determined attack' the peles were 
meant to discourage attack from largely opportunistic bands of reivers. They said: 'We're ready for you and you won't have it easy.'
The
 reivers were some three thousand years later but human nature stays 
much the same. Why invest so much time and effort into building a broch 
unless there’s somebody around who scares you? People capable of 
building a broch could, if they'd wished, have built something equally impressive and much 
more comfortable.
Who
 were the scary people? Unruly neighbours or passing armies, as with 
the reivers? Other commentators favour the idea that it was the Romans— 
but some brochs were probably built long before any possible appearance 
of any Roman ships off the Scottish coast.
Again, the truth is, no one knows -- which leads to many more fun arguments? Castles? Manor-houses? Cathedrals?
Many
 brochs seem to have had clusters of much smaller wheelhouses around 
them -- there are faint traces at Mousa. This might support the manor-house theory or make the broch a place of refuge during raids. Did they, like the peles, have a signalling 
beacon on top? Or were they look-out towers, watching for danger 
approaching from land or sea?
The
 majority of brochs are near the sea. Mousa, and the Burraland broch had
 views up and down the Shetland coast. Dun Carloway stands near a 
natural harbour on Lewis. During the time they were built, we know there
 was trade between Ireland and the islands -- and with what was
 then not yet England.
A
 natural harbour often becomes a market-place. Prosperous markets 
attract thieves and ‘trade’ easily turns into ‘raid’ and slave-taking. 
If a market town wants to keep its trade, it has to provide protection. 
Were the brochs garrisons and look-out towers, protecting a market?
In reality, the
 brochs may have had several purposes: defensive, if need be, but also 
providing advance warning of the approach of ships, for good or ill. 
They discouraged attacks by loudly declaring in stone: ‘We’re ready for 
you.’
All of which may be nonsense. Perhaps they were very
 expensive and uncomfortable prestige homes for the Iron Age plutocrat. 
What is without question is that they are astonishing feats of ancient 
ingenuity and engineering. Anyone who thinks the pre-Roman inhabitants of
 these islands were 'unsophisticated' should visit the 
Broch of Mousa.
And Maeshowe.
And Skara Brae.
Follow this link for a short video tour of Mousa Broch.
And if you're interested in more discussion about how, or if, the broch was roofed and what exactly it was used for, follow this link