Magnifying Milecastle 46: First modern excavations of the Hadrian’s Wall site begin

A new five-year project by the Vindolanda Trust is shedding unprecedented light on Magna Roman fort and nearby Milecastle 46, as well as providing invaluable data about how the local environment – and the underlying archaeology – is being affected by climate change. Carly Hilts visited Rachel Frame and Franki Gillis on site to hear the story so far.


Standing beside me on a rugged rise above Magna Roman fort, surrounded by the sounds of sheep and the gentle scrape of trowel on soil, Senior Archaeologist Rachel Frame pointed across the landscape towards a distant hill with a distinctive table-top profile. This was Burnswark, located about 30 miles away near Lockerbie in Dumfriesshire – a landmark as archaeologically important as it is visually striking, as it preserves evidence of a fierce Roman assault on an Iron Age stronghold (see CA 316). ‘For the Roman soldiers based at Magna, that was the home of the local troublemakers,’ Rachel said. ‘You could see them, and they could see you – it’s a strong reminder of why the fort was located where it was.’

Overlooking excavations north of Magna Roman fort, which are exploring the remains of Milecastle 46. The line of Hadrian’s Wall runs on the other side of the modern field boundary, and the Roman Army Museum (which will gain a new excavation centre this winter) lies in the background. The fort itself lies beneath the field adjacent to the museum.

Magna’s other key purpose was to guard the junction of two major Roman roads: the Stanegate (which runs east–west between Corbridge and Carlisle) and the Maiden Way (running north–south), both important routes for conveying supplies and information along the frontier. Like Vindolanda, the auxiliary fort lying c.6 miles to the east, Magna’s construction pre-dates that of Hadrian’s Wall, and its successive timber and stone phases would have been a dominating presence in the landscape even before they were augmented by the line of the Wall a short distance to the north. Once Hadrian’s Wall had been created, soldiers stationed at Magna could access the lands beyond it by marching out of the fort and through Milecastle 46. Generally small but heavily fortified, milecastles were evenly spaced along the Wall to control the passage of people and goods between the empire and its northern neighbours. The example at Magna would have been a vital part of this network – but today it has almost entirely vanished from view. From the post-Roman period onwards, the stonework of its walls and barracks has been systematically stripped away to be reused in other local constructions (for example, at nearby Thirlwall Castle), reducing it to a square, grassy platform in the corner of a field.

This year’s dig has uncovered the north and possibly south gates of the milecastle, as well as a Roman road that ran through it (shown under excavation).

What survives below the surface? A new five-year project by the Vindolanda Trust (supported by a grant from the National Lottery Heritage Fund) has been launched to find out. The investigations represent the first modern research excavations ever carried out on the milecastle or Magna itself, and, when I visited the dig in its first week this July, intriguing archaeological remains were already emerging from the Northumberland soil. What follows is an interim account of initial findings and the project’s future plans; watch this space for a fuller feature in the autumn, after the current investigation finishes.

The milecastle emerges

This year saw the opening of one large, square trench over the milecastle platform. Two-thirds of the structure’s footprint are thought to lie within its bounds, while the remainder is beneath a neighbouring field and outside the scope of the current investigation. Even by Day 3, things were already looking promising. As Rachel showed me around the trench, she pointed out the location of the milecastle’s north gate, through which soldiers would have ventured beyond the Wall, and outside the limits of imperial control. Its cut-through could clearly be seen, projecting in from the line of the Wall (which today lies beneath a modern field boundary), and hints of its southern counterpart, facing back towards the safety of the fort, were also beginning to emerge.

Linking these were the remains of a road surface that could be seen running along the edge of the trench, right through the middle of the milecastle. Its uppermost surface was made of large, fairly uneven cobbles, from which the team have recovered fragments of medieval green glazed pottery, but along its length patches of much neater, more typically Roman cobbling were visible underneath. Tantalisingly, LiDAR shows the route of this road continuing south beyond the excavated area, connecting the site to the nearby fort, and it is thought that this would have been the route linking Magna to the frontier, which was then reused and resurfaced in the medieval period. On the far side of the trench, the line of another possible road surface was emerging, which Rachel suggested could have provided a link to the Military Way (the Roman road running between the Wall and earthwork defences known as the Vallum, connecting all the turrets, milecastles, and forts along the frontier). Charcoal samples have been taken from these surfaces by the project’s geoarchaeologist Franki Gillis, and it is hoped that analysis of these will shed clearer light on their date.

Project geoarchaeologist Franki Gillis takes charcoal samples from a road surface.

Future plans

As for the next four years, the project’s intention is ultimately to investigate three areas around Magna and the milecastle. Area A, which will be the focus of Years 1 and 2, includes the present trench over Milecastle 46, but next year this will be joined by a long, narrow trench running in the direction of the fort. It is hoped that this will reveal more of the road surface seen in LiDAR imagery, as well as other frontier features such as the Vallum and the causeway that allowed troops to pass over it. As we walked back towards the fort, the Vallum ditch could be clearly seen, its line thickly full of reeds, hinting at damp underlying soil and the potential for anaerobic layers.

Adjacent to this was a ‘mystery feature’, which is not shown on any Roman or later records, and which will also be explored by the long trench. It comprises a narrow ditch beside a big cambered mound, and then a bigger ditch on the other side. The camber could suggest the presence of another road, Rachel said, but if so its path takes an unexpected course, and its uneven flanking ditches would be unusual for a Roman construction. Another possibility is that it forms some part of the outer defences of an earlier phase of the fort – hopefully this will become clearer as investigations progress.

In Year 3, Area B will explore the remains of a well, which lies on the edge of what deep coring has revealed to be an ancient lake. The well’s date is currently unknown, and it does not appear in surviving records, but lumps in the surrounding landscape hint at an associated structure. Another trench will investigate a series of defensive ditches and banks immediately outside the fort, which are visible as a triple arrangement on LiDAR.

Finally, Years 4 and 5 will go inside the fort itself, with Area C focusing on the south-west corner of its interior. This is where the praetorium, or administrative centre, was located – rather eccentrically for a Roman fort, as this important building was typically located right in the centre. The team wonder if Magna’s praetorium reflects the layout of an earlier phase of fort with a different footprint; with plans to excavate the entire south-western quadrant, our understanding of this may improve in the near future. They also aim to re-excavate a bathhouse that first came to light during antiquarian investigations. These remains were left exposed to view (and to weather) for some time before they were re-covered, and the team hope to assess the impact of this on the baths’ preservation – the archaeology of the archaeology of Hadrian’s Wall, as Rachel put it.

Environmental evidence

As well as learning more about the fort remains, another key aspect of the project is to gather environmental data. Climate change is having a dramatic effect on the peat that covers the site (and which has provided such good preservation conditions for the underlying archaeology), causing it to shrink back from the features buried beneath. The well is a dramatic illustration of this process: it was not visible ten years ago, Rachel said, and now perches above the surrounding field at the centre of a tall mound. The ‘mystery feature’ has risen from the ground in much the same way.

Current responses are as much about monitoring as mitigation. The project team have installed a probe and weather station outside the fort: above the surface it logs live weather conditions, while probes at different depths register changes in the water table, soil pH, and oxygen levels. At this stage, it is a matter of learning to work with the changing environment and how to continue to manage the land, Rachel said. They are looking into methods of water-management and stabilising underground conditions, but the key thing will be mitigation through excavation, documenting what can’t be saved before it disappears forever.

Further information
Magna is also home to the Roman Army Museum: http://www.romanarmymuseum.com.
The milecastle excavation will run until 22 September; during this work, trench-side visits are available on weekdays at 11.30am and 2pm for ticketholders for the museum. You can also follow progress via the dig diary: http://www.romanarmymuseum.com/magnafort/magna-dig-diary.

All images: Vindolanda Trust