Not a member?
Register and login now.

Issue 37 - Iron Age mysteries

History & Heritage

This article is available in full as part of History & Heritage, visit now for more free articles and information.


Scotland Magazine Issue 37
March 2008


This article is 10 years old and some information provided may be time sensitive. Please check all details of events, tours, opening times and other information before travelling or making arrangements.

Copyright Scotland Magazine © 1999-2018. All rights reserved. To use or reproduce part or all of this article please contact us for details of how you can do so legally.

Iron Age mysteries

The Scottish landscape is dotted with ruined stone towers known as brochs, Christopher McCooey looks how and why they were built.

In shape, and from a distance, it would have looked something like a small cooling tower. But up close, this was no smooth concrete concave structure. It was a dry-stone hollow-walled tower, entered at ground level and which had steps to take you between the two outer and inner walls up to the top. This one on Mousa, just off the mainland of Shetland, is considered to be the finest surviving example of an Iron Age broch and is some 2,000 years old.

I had come over to the island on the Solan IV from Sandwick. The captain was Tom Jamieson, known as the ‘Peerie Man’, which means the small man. He takes visitors to the island in the summer in his 60-seater boat “not the bonniest, but she’s functional.” So much so that he transports 100 sheep to and from the uninhabited 500 acre island at other times by taking out the seats.

Storm petrels find the nooks and crannies of the broch ideal for nesting and Tom will make special night time trips for visitors to see them returning in their hundreds from a day’s fishing for sand eels out at sea. Some of the birds ringed on Mousa have been picked up in their winter quarters near Cape Town.

But what are brochs and why are they unique to the north and west of Scotland?

In total, at least 700 brochs are known to exist, constructed and developed in the period between 600BC and 100AD. The actual number is likely to be much higher as there are numerous unexcavated mounds throughout Orkney, Shetland and on mainland Scotland.

A typical broch stood from five to 13 metres high (the Mousa one is the tallest at 13 metres). It was a circular two-storey, drystone structure, accessed by a single door at ground level. Beside the door, there was usually a small room breaking off from the passage and this was known as the guard cell. Inside was a main inner chamber which had a central hearth for warmth and cooking and off of this were smaller cells, either built into, or up against, the wall. To get to the upper floor and the roof top, there was a winding stone staircase, housed within the broch’s double walls.

The builders demonstrated feats of considerable architectural and engineering expertise, the key to which was the principle of double-skinned walls; this made them stronger and more stable than a single walled structure. The two outer walls were tied together at regular intervals by stone lintel slabs which allowed the constructors to build higher walls than if they were solid. In other words, our Iron Age ancestors knew a thing or two about using undressed stones shaped only by splitting, and how to build without mortar with an engineer’s understanding of force and stress.

It is not known for certain how the roof was constructed or even if there was one at all. But it is generally accepted that there was a conical timber structure at the top which would have been covered with some local thatch of reed or heather.

Structural timber may have been sourced locally or else collected from the beach.

Many of the brochs also have an underground chamber, accessed by a flight of stone steps. These may have had a water tank or well head and could be used as storage space. Or they may have had some ritual purpose, steps that led to the underworld.

There are a number of theories as to who were the builders. Some think that they were Previous page: Dun Carloway broch, Lewis; Above: Mousa Broch and the Broch of Clickimin, both on Shetland; Right: Stairs to an underground chamber inside Mousa Broch constructed by an influx of immigrants who had been displaced and pushed northward first by the intrusions of Belgic tribes into southern England towards the end of the second century BC and later by the Roman invasion that began in 43AD. Others argue that they were built by itinerant workers who may have been a hybrid of a small number of immigrants and the native population, who travelled around the north and islands and were contracted to do the work. Another theory is that the building expertise was brought by a wholesale migration into Atlantic Scotland of people from south west England. But if that was the case why aren’t there similar towers in Cornwall and Devon?

Early archaeologists had thought that maybe brochs were Viking in origin because of their location near the sea, but although some of the sites were taken over by the Scandinavians (as at Jarlshof on Shetland), radiocarbon dates on material relating to the primary use of the brochs still suggest that most of the towers were built in the first centuries BC and AD. The current thinking inclines towards those involving indigenous development.

Which brings us to why they were built.

Purely defensive? A symbol of authority?

Places of refuge for people and animals?

Because there are so many of them, maybe each broch site should be considered individually; maybe there was never a single common purpose for which every broch was constructed.

What is generally accepted is that brochs were developed from the construction of strong circular houses built by Iron Age people around 700BC. Often the home of a single family, these prototype brochs were known as roundhouses. From excavations at Bu near Stromness in Orkney, the roundhouse there was found to have a fivemetre thick outer wall. This seems to indicate that the structure was built with defence in mind. Another roundhouse at Howe just outside Stromness was excavated and the archeologists think that this too was built for defensive purposes, having walls and ditches surrounding the main dwelling.

Although defence may have played a part in the design of the broch, they may simply have been an expression of an individual or family’s social standing. In contrast to the semi-subterranean dwellings of earlier eras, the roundhouses and then the brochs towered above the surrounding landscape, reminding the locals of the power of the inhabitants and visually reinforcing their place in society.

From the Howe excavations it seems that instead of being built afterwards, the settlements surrounding brochs were constructed at the same time, so there was a kind of village community. Previously the people had lived in scattered independent dwellings but the construction of a broch meant them gathering around the powerful individual or family who ‘ruled’ over them.

The broch was a physical reminder of the villagers’ place in society, literally overshadowed by the monumental broch that dominated their daily lives. Perhaps, too, the broch was a sanctuary where the villagers gathered with their cattle and sheep when there was an attack by their enemies.

There is one curious anomaly about the location of brochs. All the Scottish brochs are to be found to the north of the Great Glen, except for a small number of them in the Forth Valley. These brochs are similar to the ones in Orkney in architectural style, which suggests some form of connection between the Orcadians and the mainland Scots.

According to Orosius, the ancient writer, the chieftains of Orkney made a formal submission to the Roman Emperor Claudius at the time of the invasion in the south in 43 AD, in essence offering to pay tribute in order to avoid devastation by the invading Romans. This sophisticated diplomatic manoeuvre had been used by some of the Gallic tribes.

Although this interpretation of Orosius has been challenged, it is a fact that the Roman general Agricola’s fleet sailed around Scotland during his fifth campaign in 83AD or 84AD. Did these ships land in Orkney?

Could the Romans have persuaded, or forced, some Orcadians to come on board and land them in the Lothians where the Votadini tribe was under Roman rule?

Another tantalising theory about how these striking, enigmatic and unique dry-stone towers came to be built in Scotland.

There are many brochs to see in Scotland, the best preserved of which are on Shetland, the Outer Hebrides and the valley of Glenelg.

Some worth visiting are: Mousa Broch on Shetland Dun Carloway Broch on Lewis Dun Telve, Glen Beag, near Glenelg Dun Troddan, Glen Beag, near Glenelg Dornaigil, near Altnaharra, Sutherland