In archaeology, a broch /b r ɒ x / is an Iron Age building made of dry stone with hollow walls found in Scotland. Brochs are part of a group called "complex Atlantic roundhouses," a term created by Scottish archaeologists in the 1980s.

Brochs are round buildings found across northern and western Scotland. The word "broch" comes from the Lowland Scots word "brough," which means a fort. In the mid-1800s, Scottish archaeologists called brochs "burgs," a term borrowed from the Old Norse word "borg," which also means a fort. Brochs are sometimes called "dùns" in the western regions. They are among the most impressive buildings of a larger group of structures found in northern Scotland. According to the Royal Commission on the Ancient and Historical Monuments of Scotland, there are about 571 possible broch sites across the country.

Scholars are still studying the origins of brochs. In the mid-20th century, some archaeologists believed brochs were built by people from southern England who moved north. However, modern research shows that brochs likely originated in what is now Scotland. The earliest brochs may have been built around 300 BC. Evidence suggests they were used mainly for defense or attack.

Brochs are most commonly found in northern Scotland, especially in Caithness, Sutherland, and the Northern Isles. A few are located in the Scottish Borders, on the west coast of Dumfries and Galloway, and near Stirling. Early archaeologists thought brochs were defensive structures where people and animals could take shelter. Some believed they were built by the Danes or Picts. From the 1930s to the 1960s, archaeologists thought brochs were like early castles, where local leaders controlled nearby communities.

However, this idea became less popular in the 1980s because no strong evidence supported it. Instead, archaeologists suggested brochs might have been homes for important families, showing their status and power. This theory also lacks clear evidence, and the large number of brochs makes it hard to confirm. The article concludes that brochs may have served multiple purposes, including defense, attack, and as symbols of importance.

Origin and definition

The word "broch" comes from the Lowland Scots word "brough," which means "fort" among other things. In the mid-1800s, Scottish experts called brochs "burgs," which comes from the Old Norse word "borg," also meaning "fort." Place names like Burgawater and Burgan in Scandinavian Scotland show that "borg" was the older term used for these structures in the north. In the western areas, brochs are sometimes called "dùn." Experts began using the spelling "broch" in the 1870s.

It has been hard to create a clear definition for the word "broch." Brochs are the most impressive of a complex group of roundhouse buildings found throughout Atlantic Scotland. The Shetland Amenity Trust lists about 120 sites in Shetland as possible broch locations. The Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) has identified 571 possible broch sites across the country. Researcher Euan MacKie, using a more limited definition, suggests there may be as few as 104 brochs in Scotland.

The origin of brochs is still being studied. About 80 years ago, most archaeologists believed brochs, often seen as the "castles" of Iron Age chieftains, were built by people who moved north after being displaced by the Belgic tribes in southeast England around 200 BC and later by the Roman invasion of southern Britain starting in AD 43. Today, experts agree that the broch tower was created in what is now Scotland. Even the pottery styles found inside brochs, which resembled those from southern Britain, were local versions.

The first modern review (MacKie 1965) did not, as some believe, suggest brochs were built by immigrants. Instead, it proposed that a mix of a small group of immigrants and the native Hebrides population created brochs in the 1st century BC, based on earlier, simpler forts. This idea was different from Sir W. Lindsay Scott's, who, following V. Gordon Childe (1935), believed many people from southwest England moved to Atlantic Scotland.

MacKie's theory is no longer widely accepted because, starting in the 1970s, archaeologists moved away from "diffusionist" ideas (which suggest outside influences) to theories focusing on local development. Although few radiocarbon dates exist for when brochs were first built, the available data suggests most were constructed in the 1st centuries BC and AD. A few may be older, like the Old Scatness Broch in Shetland, where a sheep bone dated between 390 and 200 BC was found.

Another broch, Crosskirk in Caithness, was once thought to be older than the 1st century BC. However, recent studies suggest it was likely built around the same time as the 1st centuries BC and AD.

Distribution

Brochs are mainly found in northern Scotland. The areas with the most brochs include Caithness, Sutherland, and the Northern Isles. Many brochs are also found in western Scotland and the Hebrides. While most brochs are located in the northern Highlands and Islands, a few are found in other regions, such as the Borders, the west coast of Dumfries and Galloway, and near Stirling. For example, Edin's Hall Broch and Bow Castle Broch are in the Borders. A drawing from around 1560 shows a broch near Annan Castle in Dumfries and Galloway. The small number of brochs in the south of Scotland has not been fully explained.

Purposes

The original idea about brochs, which was popular among early researchers in the 19th century, was that they were strong buildings used to protect communities and their animals. Some people thought they were built by the Danes or the Picts. From the 1930s to the 1960s, archaeologists like V. Gordon Childe and John Hamilton believed brochs were castles where local leaders controlled nearby people.

This castle idea became less popular in the 1980s because no strong evidence was found to support it. Instead, some archaeologists suggested brochs might have been large homes that showed the importance and power of wealthy families. However, there is still no clear proof for this idea. The large number of brochs, even in areas with poor land, makes this theory difficult to support.

Brochs are often found in groups and are common in many areas. This might mean they were used for defense or attack. Some brochs were built near steep cliffs and protected by natural or man-made barriers. For example, one in Shetland, near Burland, is on a cliff and surrounded by large ditches. Brochs are often placed in important locations. In Shetland, some are on opposite sides of narrow waterways, like the Broch of Mousa and another at Burraland. In Orkney, more than a dozen brochs are found on both sides of Eynhallow Sound, and many are near the entrances of Scapa Flow. In Sutherland, brochs are often located along the edges of deep valleys. In 1956, John Stewart suggested that brochs in Shetland were forts built by a military group to watch over and protect the land and sea.

Some archaeologists now believe each broch might have had a different purpose. Brochs vary in where they are built, their size, and their likely importance in different areas. For example, groups of brochs found in Orkney are not seen in the Western Isles.

Structures

Brochs typically have one entrance with bar-holes, door-checks, and lintels. Inside, there are mural cells and a scarcement, which may have been used for wooden lean-to buildings along the inner wall. A spiral staircase connects the inner and outer walls and links the galleries. Brochs range in size from five to fifteen meters (16 to 49 feet) in diameter, with walls up to three meters (9.8 feet) thick. Most broch walls survive only a few meters in height. Five broch towers have walls taller than 6.5 meters (21 feet): Dun Carloway on Lewis, Dun Telve and Dun Troddan in Glenelg, Mousa in Shetland, and Dun Dornaigil in Sutherland.

Mousa’s walls are the best preserved and still stand 13 meters (43 feet) tall. It is unclear how many brochs originally had walls of this height. Broch walls often have galleries, with open space between the inner and outer walls connected by stone slabs that may have served as steps to higher floors. A guard cell, a small room near the entrance, is common in some brochs. In Shetland, guard cells are sometimes found near large door-check stones. Some archaeologists now believe brochs were roofed with conical wooden frames covered in local thatch, though evidence for this is limited. Excavations at Dun Bharabhat on Lewis may support this idea. Finding sources of structural timber remains a challenge, though bog and driftwood may have been used.

Few brochs on Orkney and Shetland have ground-floor cells. Most have scarcements, which may have supported wooden first floors, as noted by George Low in Shetland in 1774. Excavations at Loch na Berie on Lewis suggest some brochs had a second floor, with stairs on the first floor leading upward. Brochs like Dun Dornaigil and Culswick in Shetland have triangular lintels above their entrance doors.

Brochs were sometimes built near arable land and water sources, such as wells or springs. Others were located in remote areas, like Levenwick and Culswick in Shetland or Castle Cole in Sutherland. Many brochs are near the sea, such as Carn Liath in Sutherland, or on islands in lochs, like Clickimin in Shetland.

About 20 broch sites in Orkney include small stone settlements surrounding the main tower. Examples include Howe near Stromness, Gurness Broch on Mainland, Midhowe on Rousay, and Lingro near Kirkwall (destroyed in the 1980s). "Broch village" sites exist in Caithness but are rare elsewhere.

Most brochs remain unexcavated. Broch construction likely ended around AD 100–200. Excavated brochs show they were used for centuries, with interiors often modified and abandoned multiple times.

Heritage status

The Iron Age sites of Mousa, Old Scatness, and Jarlshof in Shetland are listed on the United Kingdom's "Tentative List" for possible inclusion in the UNESCO World Heritage list. This list, released in July 2010, includes locations that may be considered for official recognition as sites of great cultural or natural significance to the shared heritage of all people. These sites could be nominated for inclusion in the future, likely within the next 5 to 10 years.

New broch planned

The Caithness Broch Project was created in 2013 as an experimental archaeology project to build a broch using traditional methods, such as drystone walling. The goals of the project include learning more about the purpose of brochs, keeping local skills like drystone wall building alive, and drawing visitors to the area. As of 2022, a site had not been chosen, and the needed funding, estimated to cost between £1 million and £3 million, had not yet been secured.