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Caerleon Legionary Fortress

Priory Field Excavations 2007-2010

Project Background

The excavations undertaken in Priory Field are linked to a broader research project entitled Mapping Isca: the legionary fortress at Caerleon and its environs, which aims to investigate the layout, development and history of the fortress, its garrison and the population of the settlement beyond the fortress walls (the canabae). This project is supported by the Caerleon Research Committee(

Three legions were permanently garrisoned in the Roman province of Britannia. The other legionary bases are beneath the cities of Chester and York where excavation of the remains of Roman fortresses is very difficult. This means the archaeology at Caerleon is unique in Britain and important for the entire Roman Empire.

In 2004, Glamorgan-Gwent Archaeological Trust, supported by Cadw, produced 'The Roman fortress at Caerleon & its Environs: a Framework for Research'. This document emphasised the layout of the fortress and the civilian settlement (canabae) outside its walls as research priorities, and also highlighted the potential of previously uninvestigated parts of the fortress, such as Priory Field, to produce significant results.

As a result of these recommendations Cardiff University and Cadw commissioned extensive geophysical surveys of areas of the fortress and its canabae, which have been undertaken since 2006 (see Guest and Young 2007). In 2007 Cardiff University and UCL excavated a series of evaluation trenches to investigate some of the buildings located by the geophysical surveys, to evaluate the character of the surviving archaeology in Priory Field and to examine a building excavated in Golledge's Field in the 1930s. An interim report on this work is available on the Caerleon Research Committee website

Caerleon from the air (Crown copyright: Royal Commission on the Ancient and Historical Monuments of Wales)
Caerleon from the air (Crown copyright: Royal Commission on the Ancient and Historical Monuments of Wales)

The 2008 and 2010 Priory Field Excavations

In the summer months of 2008 and 2010, the UCL-Cardiff excavation team opened up a large trench on the site of a probable warehouse building identified in the survey work. This building promised to be revealing of aspects of legionary life that have hitherto been neglected, and we also hoped to shed light on the later phases of the fortress. Our results very clearly satisfied both of these objectives.

This excavation was particularly important as the first research excavation conducted on a military store-building building in Britain: store-buildings are a largely unknown feature of legionary fortresses not just in Britain, but across the empire. While buildings of potentially similar function have been located in fortresses along the Rhine and Danube, these structures have not been excavated using modern techniques like those being employed at Caerleon.

The building excavated in Priory Field appears to be a square structure, with a large inner courtyard surrounded by four ranges of rooms, and is some 50m long on each side. The whole of the western wing lies within Priory Field, and our trench straddled this wing of the building, including parts of the yards on either side. The preliminary interpretation of our results is that there are three main periods of activity on the site: the Roman ‘warehouse’, an intermediate phase of structures, and a Medieval agricultural building.

The warehouse was probably constructed in the late 1st century AD, as one of the first stone buildings in the fortress. Although its walls had been heavily robbed, traces of the main external walls, internal partitions, and some areas of flagstone flooring were all uncovered. In addition to four complete store-rooms, we excavated an entrance passageway (or carriageway), flanked by small areas interpreted as a possible stairwell and a 'porter's lodge'. This entrance to the building had been resurfaced later in the Roman period. Finds from the store-rooms included a wide range of military fittings (see our gallery), and some incredibly well-preserved segments of armour.

Above the level of the masonry store-building was a series of incomplete lengths of walling relating to an intermediate phase of structures. These walls were unmortared and unfounded, and yet appeared to have stood to at least one-storey in height, judging from an area of wall-collapse. Indications from their relationship to the warehouse walls suggest that the new phase of structures were erected in and around the partially-ruined or demolished warehouse, perhaps in the late Roman period or early in the succeeding period.

The third and final major structural phase appears to belong to a much later time. Overlying all of the remains described so far, a very broken-up flagged area in the centre of the trench appeared to be the remains of another building, associated with a flag-lined pit, perhaps a grain-bin. Our interpretation of this structure is as a Medieval cow-shed or stable. The sequence of buildings so far recorded thus gives a fairly complete indication of the transition from Roman fortress into Medieval farm.

In addition to the project's research objectives, we have been very keen to engage visitors in the dig, holding very successful public open days and tours in both 2008 and 2010. Over the two years of large-scale excavation, we welcomed some 7,000 visitors to the site, and this blog site received nearly 40,000 hits!

For more details on the excavations, including some of our major finds, see the 2008 and 2010 excavation blogs and also the interim reports on the CRC website (

Excavations in 2008: alterations to the Roman warehouse
Excavations in 2008: alterations to the Roman warehouse


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More about the project directors

Project Sponsors and Supporters

We are very grateful for the support of:
Cadw, Cardiff University, UCL, National Roman Legion Museum, the Caerleon Research Committee, Current Archaeology, and the Caerleon community.


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