The Roman Empire – Hadrian’s Wall , Great Britain

Words: David BiggsIn this article, we travel to the island of Great Britain, a land known for its Marvelous Masonry. From such icons as Stonehenge, Westminster Abbey, Big Ben Clock Tower, and their brick arch railway bridges, masonry has been the dominant building material for generations, and British craftsmanship is well known.

Before the official founding of England, the Roman Empire was a main influence on the development of the British Isles, and this included the building of Hadrian’s Wall.

Hadrian’s Wall
Rome began its conquest of modern-day Britain in 43 AD under Emperor Claudius. By the 2nd century AD, the Romans controlled what is now England and Wales. Roman military campaigns pushed northward into Caledonia (now Scotland) but could not maintain control due to the harsh terrain and fierce resistance from local tribes (Caledonians, Picts, and others).

Historians still disagree as to the loss of approximately 5,000 Roman soldiers of the Ninth Legion that disappeared from Roman records. The legend of the Ninth was the subject of novelist Rosemary Sutcliff, whose historical children’s novel, The Eagle of the Ninth, became an instant bestseller when published in 1954. In 2011, the book was adapted to the film, The Eagle, and available on Netflix.

In 117 AD, Hadrian became emperor of Rome. His reign shifted Roman policy from expansion to consolidation and defense. In 122 AD, he visited Britain and ordered the construction of a wall to mark the northern boundary of the Roman province of Britannia and control movement, prevent raids by tribes, and demonstrate the might and reach of the Roman Empire. Whether the loss of the Ninth Legion had an impact on his decision is unknown.

Emperor Hadrian's predecessor, Emperor Trajan, had significantly expanded the Roman Empire's borders to their greatest extent, reaching as far as Mesopotamia in the east. The Empire's borders were overstretched, creating difficulty in maintaining control and defense. Hadrian's focused on strengthening and securing the existing frontiers rather than pursuing new conquests. This strategy included withdrawing from some of Trajan’s conquests, such as Mesopotamia, which he deemed unsustainable, and solidifying the Empire’s boundaries through fortifications like Hadrian's Wall in Britain.

Hadrian’s Wall was extended coast to coast and stretched approximately 73 miles, (east of modern-day Newcastle to the west of modern-day Carlisle) as shown in Figure 1.

Note: Centuries earlier, the Great Wall of China (between 5,500 miles and 13,000 miles long) was constructed to defend against invasions. There is no record that the Great Wall influenced Hadrian.

Figure 1 – Hadrian’s Wall
(Credit: By Hadrians_Wall_map.png: Created by NormanEinstein, September 20, 2005derivative work: Talifero (talk) - Hadrians_Wall_map.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15121382)

The wall was designed to be about 15 feet high and 8-10 feet wide and constructed primarily of stone. In some areas, particularly in the western parts, the wall was constructed from turf due to the lack of suitable stone.

In addition to the wall, a sophisticated network of ancillary structures was built. Watch towers, or milecastles (Figures 2 and 3), were erected every Roman mile, These towers were constructed similarly to the wall itself. Few milecastles are remaining; most of them and the wall have been deconstructed over the generations to be used to construct homes, churches, farm walls, and other buildings.

Figure 2 - Graphical representation of Hadrian's Wall and a Milecastle

Figure 3 – Artist rendition of Hadrian’s wall and a Milecastle (credit AncientVision.com)

Between the milecastles, there were two turrets (Figures 4 and 5) to provide additional observation points and housing for garrison troops. Finally, a series of forts were constructed away from the wall to garrison troops (Figure 6).

Figure 4 – Graphical representation of wall and turret at Banks East, Cumbria
(credits: by Philip Corke, distributed by Almy)

Figure 5 – Remnants of Hadrian’s wall and turret (arrow)

Figure 6 - Archeological site of Roman fort at Vindolanda

The construction of Hadrian's Wall was a significant engineering feat that highlighted Roman expertise in building and logistics involving thousands of soldiers and local laborers. The primary materials used were locally sourced stone, lime for mortar, and turf in some sections. The stone construction involved laying stone blocks in courses, with rubble and smaller stones used to fill the core. Mortar, made from lime, was used to bind the exterior stones together. The rubble core was filled with either clay or lime mortar.

Construction began with the foundation trench excavation, which was crucial for ensuring stability and longevity. After the trench, a stone foundation was laid, often composed of a layer of large, flat stones arranged to create a solid base (Figure 7). Over the centuries, the stones were quarried away leaving short walls and thinner walls. Figure 8 shows missing dressed stones on the left side (arrow).

The wall had outer wythes of dressed stone and a core of smaller stones or rubble. The wall was finally capped with dressed stone (Figure 9). In the turf sections, the construction involved laying thick layers of turf blocks, sometimes reinforced with wooden planks to help bind the material and add stability.

Figure 7 – 10 ft wide base of wall; dressed outer stones; at Birdoswald

Figure 8 - Reduced width wall (approx. 6 ft) from missing dressed stones (arrow) at Birdoswald

Figure 9 – Capstones

Stone Walls: Hadrian's Wall was primarily built using locally sourced stone. The terrain was quite variable (Figure 10). The goal was to minimize transporting the stone.

Figure 10 – Variable terrain at Steel Rigg, Northumberland

The types of stone commonly used varied depending on the specific location and included:
• Sandstone: This was the predominant stone material widely available and could be easily quarried and shaped. The quality and durability of the sandstone made it suitable for building the wall's substantial structures.
• Limestone: For some sections where sandstone was less accessible, limestone was used. It also is a durable and workable material.
• Dolerite (local Whinstone): In some areas, the local stone was Whinstone, an extremely hard stone that can be either igneous or sedimentary. Its key feature is its hardness making it durable but more difficult to quarry and shape compared to sandstone and limestone (Figure 11).

Figure 11- Whinstone at Steel Rigg

Turf Walls: For the western sections of the wall, a lack of suitable stone led to using turf blocks cut from the surrounding landscape and stacked to create a substantial earthen rampart, which was then faced with stone to protect it from erosion.

Ditches and Vallum: A large ditch, known as the Vallum, was dug parallel to the south of the wall. This ditch was about 20 feet wide and 10 feet deep, with a flat-bottomed design. The earth excavated from the ditch was used to create a berm (a raised bank) and two mounds, which added to the defensive features of the wall.

Forts, Milecastles, and Turrets: The forts were constructed of stone at intervals along the wall and included barracks, granaries, commander's houses, and other essential buildings. Milecastles and turrets were built of stone and timber.

Bridges: There were many water crossings. The wall was constructed through a series of bridges (Figure 12) using the materials and techniques.

Figure 12 - Artist's illustration of the original bridge (2nd century AD) incorporated into the famous wall
(Credit: Nigel Cole, https://www.nigelsphotoblog.co.uk/2021/07/willow-bridge-on-hadrians-wall-left.html?m=1)

Antonine Wall
Emperor Hadrian died in 138 AD and was succeeded by Emperor Antoninus Pius who had one of the most peaceful reigns as a Roman Emperor. But he chose to expand the empire north beyond Hadrian’s Wall into modern-day Scotland. In 142 AD, he ordered the building of a second wall, the Antonine Wall, as seen in Figure 1. It was constructed 37 miles long and ran east to west across the narrowest part of central Scotland, between the Firth of Forth and the Firth of Clyde.

The Antonine Wall was constructed using a variety of materials, primarily earth, turf, stone for foundations, and timber. The wall also featured deep pits that would have had sharp spikes in them. These helped to make the wall harder to attack. Sixteen Roman forts were built along the length of the wall to help protect it.

It took around ten to twelve years to build the Antonine Wall but, after only eight years of defending it, the Romans pulled back from the wall and retreated around 162 AD to northern England behind the safety of Hadrian’s Wall that they had built twenty years earlier. Little remains of the Antonine Wall because so little was constructed of stone. What remains today are primarily earthen ditches and stone bases for the wall.

Summary
Hadrian's Wall is the largest Roman archaeological feature in Britain. It is regarded as a British cultural icon. Designated as a UNESCO World Heritage Site in 1987, it is one of Britain's major ancient tourist attractions.

Other than reconstructions, no full-height sections of Hadrian's Wall remain. The ravages of time, including weathering, stone robbing, and agricultural activities, have significantly reduced its height. The most intact portions of the wall generally reach a height of around 6 to 10 feet. But visitors can still get a sense of the wall's original scale and the formidable nature of this Roman frontier defense. Can’t make the trip yourself? There are many great images and videos available just by searching “videos Hadrian's wall” in Google.

Cultural tourism is a significant economic generator in many countries. Interpretative signage, visitor centers, and walking trails along Hadrian’s Wall’s route help to explain its history and significance, allowing us to appreciate the scale and impact of this ancient Roman fortification. I became increasingly interested in Hadrian’s Wall after speaking with a distinguished professor (Beth Dusinberre) while we were working at an archeological site in Türkiye. She had hiked its entire length, and her experiences led me to visit this example of Marvelous Masonry (thanks Beth!).

I realized that the principles of durability and foundation stability in Roman design remain relevant to contemporary construction practices. They used quality materials, solid stone foundations, layered with rubble and capped with carefully dressed stones, which mirrors modern techniques. The British people have also embraced sustainability by reusing the stone from the wall. We only wish they had left more intact for us to admire!

Author: David Biggs is a US-based consultant and regular columnist for Masonry (Marvelous Masonry series) and Masonry Design (Technical Talk) magazines. He is a PE and SE with Biggs Consulting Engineering, Saratoga Springs, NY, USA (www.biggsconsulting.net), and an Honorary Associate Professor with the University of Auckland, NZ. He specializes in masonry design, historic preservation, forensic evaluations, and masonry product development. David was a Fulbright Specialist in Portugal in 2023. AI was used in the development of this article.

The Roman Empire – Hadrian’s Wall , Great Britain

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