In archaeology, a broch (pronounced "broch") is an Iron Age building made of dry stone with hollow walls, found in Scotland. Brochs are part of a building category called "complex Atlantic roundhouse," created by Scottish archaeologists in the 1980s.

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

The origin of brochs is still being studied. In the mid-20th century, some archaeologists believed brochs were built by leaders from southern England who moved north. However, it is now clear that brochs first appeared 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 mainly found in northern Scotland, with the highest numbers 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 ideas suggested brochs were defensive buildings where communities and their animals could take shelter. Some thought they were built by Danes or Picts. From the 1930s to the 1960s, archaeologists believed brochs were like early castles where local leaders controlled nearby people.

However, the "castle" idea became less popular in the 1980s because there was no strong evidence to support it. These archaeologists argued that brochs were not built for defense and may have been "stately homes" of their time, showing the power and status of important families. However, there is no clear evidence for this idea, and the large number of brochs makes it hard to prove. The article concludes that brochs may have served multiple purposes, including defense, attack, and symbolism.

Origin and definition

The word broch comes from the Lowland Scots word brough, which means a type of fort. In the mid-1800s, Scottish historians called brochs burgs, after the Old Norse word borg, which also means a fort. Place names like Burgawater and Burgan in northern Scotland show that borg was the older word used for these structures. In western Scotland, brochs are sometimes called dùn, a Scottish Gaelic word. Historians started using the spelling broch in the 1870s.

There is no single, clear definition for the word broch. Brochs are the most impressive type of roundhouse buildings found in Atlantic Scotland. The Shetland Amenity Trust lists about 120 possible broch sites in Shetland, while the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) records 571 possible broch sites across the country. Researcher Euan MacKie, using a strict definition, estimated there are about 104 brochs in Scotland.

The origins of brochs are still being studied. Many years ago, most archaeologists thought brochs were built by people who moved north after being pushed out of southeast England by Belgic tribes around 200 BCE and later by the Roman invasion of Britain starting in 43 CE. However, today it is clear that brochs were invented in what is now Scotland. Even the pottery found inside them, which looked similar to styles from southern Britain, was a local version.

A major review of broch research in 1965 (by Euan MacKie) did not suggest brochs were built by immigrants. Instead, it proposed that a mix of a few immigrants and the native people of the Hebrides created brochs in the 1st century BCE, building on earlier, simpler forts. This idea contrasted with the belief of Sir W. Lindsay Scott, who followed V. Gordon Childe (1935) and argued that many people from southwest England moved to Atlantic Scotland.

MacKie’s theory is no longer widely accepted, as archaeology has shifted away from ideas that rely on outside influences to ones that focus on local development. However, the limited number of radiocarbon dates for brochs (from their original use, not later use) suggests most were built in the 1st centuries BCE and CE. A few may be older, such as the Old Scatness Broch in Shetland, where a sheep bone dated to 390–200 BCE has been found.

Another broch, Crosskirk in Caithness, was claimed to be older than the 1st century BCE. However, recent studies suggest it cannot be dated earlier than the 1st centuries BCE and CE.

Distribution

Brochs are mainly found in northern Scotland, with the highest numbers in Caithness, Sutherland, and the Northern Isles. Many brochs also exist in western Scotland and the Hebrides. While most brochs are located in the northern Highlands and Islands, a few are found in the Borders, such as Edin's Hall Broch and Bow Castle Broch, along the west coast of Dumfries and Galloway, and near Stirling. A drawing from around 1560 shows a broch near Annan Castle in Dumfries and Galloway. The small number of brochs in southern areas remains unexplained.

Purposes

In the 1800s, some experts thought brochs were places where people and animals could stay safe during attacks. They sometimes believed these structures were built by Danes or Picts. From the 1930s to the 1960s, archaeologists like V. Gordon Childe and John Hamilton thought brochs were castles where local leaders controlled nearby people.

By the 1980s, many Scottish archaeologists no longer supported the castle idea because there was no strong evidence to back it. These experts argued that brochs were not built for defense and may have been large homes that showed the importance of powerful families. However, there is still no clear proof to support this idea. The large number of brochs, even in areas with poor land, makes this theory difficult to confirm.

Brochs are often found in groups and in many places, which may suggest they had a defensive or offensive purpose. Some brochs were built near steep cliffs and protected by natural or man-made barriers. For example, one in Shetland is on a cliff and surrounded by large ditches. Brochs are often located at important places, such as narrow waterways or near harbors. In Shetland, brochs sometimes appear on both sides of narrow water stretches, like the Broch of Mousa and another in Sandwick. In Orkney, more than a dozen brochs are found on opposite sides of Eynhallow Sound, and many are near the entrances of Scapa Flow. In Sutherland, brochs are often placed along the edges of deep valleys. In 1956, John Stewart suggested that brochs in Shetland were forts used by a military group to watch over and protect the land and sea.

Some archaeologists study brochs individually and believe each may have had a different purpose. Brochs vary in location, size, and possible importance depending on where they are found. For example, groups of brochs in Orkney, called "broch villages," are not found in the Western Isles.

Structures

Brochs typically have one entrance with bar-holes, door-checks, and lintels. They include mural cells and a scarcement (ledge), which may have supported timber-framed lean-to dwellings 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 three meters (9.8 feet) thick. On average, the walls remain only a few meters high. Five broch towers have walls that are significantly taller: Dun Carloway on Lewis, Dun Telve and Dun Troddan in Glenelg, Mousa in Shetland, and Dun Dornaigil in Sutherland. These towers have walls over 6.5 meters (21 feet) tall.

Mousa’s walls are the best preserved and are still 13 meters (43 feet) tall. It is unclear how many brochs originally had walls this high. Brochs often have galleried walls, with open space between the outer and inner walls. These walls are connected by linking stone slabs, which may have acted as steps to higher floors. A guard cell, a small room near the entrance passage, is common. In some Shetland brochs, guard cells are located near large door-check stones. Although there was debate in the past, some archaeologists now agree that brochs were likely roofed with a conical timber frame covered in local thatch. Evidence for this is limited, but 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 (ledges) that may have supported a wooden first floor, as noted by George Low in Shetland in 1774. Excavations at Loch na Berie on Lewis suggest some brochs may have had a second floor, indicated by stairs 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 within 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 in northwest Mainland, Midhowe on Rousay, and Lingro near Kirkwall (destroyed in the 1980s). "Broch village" sites exist in Caithness, but not 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 Programme. This list, published in July 2010, includes locations that might 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 started in 2013 as a type of archaeology that uses hands-on methods to build a broch using traditional techniques, such as drystone walling. The goals of the project are to learn more about the purpose of brochs, keep local building skills alive, and bring visitors to the area. As of 2022, the project had not yet found a place to build, and the needed money, which is estimated to be between £1 million and £3 million, had not been secured.