As the Bronze Age drew to a close, the people of Wales
built dozens of peculiar structures called “hillforts” –
but nobody knows why
From the top of the 440m-tall hill of Penycloddiau, the
Clwyddian Range of northern Wales spreads out before you.
It is easy to think that the beautiful view is the real attraction
here. After all, unless you are an archaeologist, the roll that
borders Penycloddiau’s summit – like a heather- and gorse-
topped bumper – might seem like a natural phenomenon.
It is not.
“I can die happy now” – When Alex met his idols…
Our ultimate Rolling Stones Fan of London was pretty
excited to find out he was coming to London for an exclusive
look at Exhibitionism, but what he didn’t expect was to meet
Discover London’s music scene
Fiona Gale, archaeologist for Denbighshire County who
spearheaded the Heather and Hillforts project, stops on
the dirt path. She points to a bump in the land next to us.
“Presumably, there would have been a gate here, and a
palisade-like fence all the way around,” she says. The other
roll of land, just a few feet away? “A guard chamber.”
These features are far from incidental. They are man-made,
built around 3,000 to 2,500 years ago.
But nobody knows what these structures, dubbed “hillforts”,
were used for. Were they for defence, as their name
suggests? Settlement? Storing grain? Showing off?
Take that “guard chamber”. It could indeed have been a
place where a military guard stood to protect the enclosure.
But it could also have been a shrine: a place for those
entering or leaving to pray or give thanks.
In an area that measures some 150 square miles (389 sq
km), there are about 30 hillforts
“The language of these things was established in the early
20th Century when we were fighting a lot of wars: hillforts,
guard chambers,” Gale says, a little ruefully. “We’re stuck
with these terms. But I think they were much more
complicated than just being military or defensive.”
Enclosing an area of 21 hectares (51.8 acres), Penycloddiau
is the biggest hillfort in northern Wales
The wall that surrounds it, now buried beneath dirt, heather
and gorse, was some 13ft (4m) thick. Stone-faced on the
inside and the outside, with a rock-cut ditch below and likely
with timbers on top, it would have towered an imposing
33-39ft (10-12m) tall.
The structure would have been visible for miles. And it
would have taken a great deal of work and organisation to
build. The timber alone needed would have required around
170 hectares (420 acres) of woodland.
Yet as extraordinary as it is, Penycloddiau is hardly the only
hillfort in this area – or in Britain.
Similar hilltop enclosures are particularly common in
southern England, less so in Wales or Scotland. But this
section of Wales is thick with them. In an area that measures
some 150 square miles (389 sq km), there are about 30
It would be very difficult for a group to defend a hillfort
This adds to their mystery. It is a surprising number for a
region that, at the time, did not have a particularly dense
So why were they built at all?
The name hillfort, of course, suggests the enclosures were
built for a military purpose. But there are problems with the
simplicity of this explanation.
“It would be very difficult for a group to defend a hillfort,
especially one the size of Penycloddiau,” says University of
Oxford archaeologist Gary Lock, who is leading an
excavation at the nearby Moel-y-Gaer hillfort. “How
many hundreds and hundreds of people would you need to
defend that? Then, at the same time, you need another great
group of people attacking it. There just isn’t that level of
Warfare in small-scale societies tends to be heavily
ritualised, full of rules and conventions
There are other flaws with the idea, too. For example, few of
the area’s forts have their own water source.
Meanwhile, hardly any weapons have been found. This is
true for weapons of that time in general – it is much more
common to find weapons from the previous era, the Bronze
One reason might be that, by this period, the preferred
weapon seemed to have been slingshot stones. These have
been found in hillforts, but generally not in sufficient
numbers to suggest a full-scale battle.
Still, the idea that an organised group would bring a cartload
of stones up to an enemy hillfort seems a little absurd.
Ian Armit of the University of Bradford has tried to figure
out how defensive these hillforts really were, by looking at
more recent structures in other cultures.
At the end of the Bronze Age, this elaborate system of
wealth and trade collapsed
He has found that warfare in small-scale societies tends to
be heavily ritualised, full of rules and conventions. Siege
warfare “is not something that often happens”, he says. “It’s
seen as cowardly or unfair.”
In that context, even a lack of water can be explained. In
fact, Armit points out, when Julius Caesar was attacking Iron
Age hillforts in Gaul, the Roman general wrote about how his
soldiers would attack the enemy when they left their forts to
But if warfare at the time meant skirmishes, not sieges, why
build a hillfort at all?
To understand that, it is important to understand the shift
from the Bronze Age to the Iron Age.
From about 4,000 to 2,800 years ago in Britain, bronze was
the primary way to build alliances and trade networks
across communities. Society was more organised, warfare
tended to happen on a grander scale, and the weapons were
more glorious. That may be why it is easier to pick these
weapons out of the archaeological record.
But at the end of the Bronze Age, this elaborate system of
wealth and trade collapsed.
It’s probably to do with people coming together to ensure
that crops don’t fail
The reasons remain mysterious. We know that the climate
had been deteriorating in parts of Britain. We also know
that iron – probably introduced to Britain by continental
Europeans – was replacing bronze as the metal of choice.
“It’s a bit like a bank crash,” says Niall Sharples of Cardiff
University. “They get to the state where everything revolves
around bronze and the exchange of bronze. Then external
factors cause that to collapse, no one has faith in the system
and they have to find another way.”
The crisis is thought to have ushered in the change to what
we call the Iron Age. In Britain, this lasted from roughly
2,800 years ago to the Roman invasion 1,900 years ago.
At about the same time, hillforts begin to be constructed in
A few reasons may help illustrate why. First, in the absence
of those long trade routes and of exchanging bronze as a
way to secure friendship, society itself became more
fragmented. No longer able to depend on far-flung allies,
groups became more self-sustaining and insular.
Meanwhile, the effects of the changing climate made
farming a riskier business. As a result, people may have
pooled resources; for example, storing their grain together.
In fact, storage pits have been found in a number of
I think they were much more complicated than just being
military or defensive
“I think the origins of hillforts probably do have a lot to do
with what happens at the end of the Bronze Age [in terms of
climate] – which we know had quite an effect out here,” says
the University of Liverpool’s Rachel Pope, who is leading the
excavations at Penycloddiau. “It’s probably to do with
people coming together to ensure that crops don’t fail, to
ensure that animal herds survive.”
And third, no longer able to flash their power with bronze, a
tribe or group might have turned to a different kind of status
symbol: a hilltop structure – one that required significant
manpower, resources and, of course, that could be seen for
By making a statement of prestige and group identity, as
well as being a place to store grain, a hillfort may have
helped people accomplish several goals at once. If it could
keep them safe from potential enemies, so much the better.
Hillforts also may have doubled as settlements – though not
Once again, archaeologists run into a vexing lack of artefacts
showing this. But that does not mean the settlement theory
is wrong. In the Iron Age in the area, people did not use
pottery. And in the acidic soil of the Welsh hills, metal and
bone both disintegrate. This all makes hard evidence hard to
We can see that it’s certainly more to do with agriculture
As a result, the most you might expect to find is a burn pit,
which was turned up at Moel y Gaer, Llanbedr in 2009. Or
something handmade but stone, such as a spindle wheel
showing weaving activity – which was exactly what Lock’s
team found at Moel y Gaer, Bodfari. (Moel y Gaer means
“fortress hill” in Welsh).
Then there are the imprints left from buildings.
On Penycclodiau, Pope and her team identified 82 potential
roundhouse platforms, some of them around a spring. They
are currently excavating one of them. “The traces of
occupation are often quite fragile,” Pope says. “We haven’t
found anything as straightforward as a hearth yet. But we do
have postholes in the interior.”
At this point, Pope thinks that settlement at Penycclodiau
was mainly seasonal.
“When we look at the origins of hillforts in Britain, we can
see that it’s certainly more to do with agriculture than
defence, that it’s as much about bringing animals into space
as people,” she says. “Settlement in many cases – not in all
cases, but in many cases – seems to be relatively temporary.
The houses aren’t terribly steadfast.”
That is part of the fascination I have with hillforts: the not
Will we ever know for sure why hillforts sprang up across
Britain? Probably not.
But the possibility remains that the ongoing excavations in
the Clwyddian Range will yield more clues. Many of the
hillforts here have never been excavated, or were only
studied decades ago, when archaeologists were much less
systematic than they are today.
“The more we do and the more carefully we do it, the more
we’ll get answers, but we’ll never get all of them,” Gale says.
“That is part of the fascination I have with hillforts: the not
This story is a part of BBC Britain – a series focused on
exploring this extraordinary island, one story at a time.
Readers outside of the UK can see every BBC Britain story
by heading to the Britain homepage; you also can see our
latest stories by following us on Facebook and Twitter.