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Caerleon Legionary Fortress

Priory Field Excavations 2008 and 2010

The Aims of the Project

The results of the excavation of the courtyard building will provide us with new information about the storage facilities, provisioning and supply of a legion in Britain. Also, there are already good indications that the site holds important evidence concerning the history of Caerleon at the end of the Roman period in Britain, when it is believed that the Second Augustan Legion was moved from Isca to Cardiff and finally Richborough in Kent.

This is 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.

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.

Project Background

The excavations being 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 Priory Field Excavations

In June and July 2008, the UCL-Cardiff excavation team opened up a large trench on the site of a possible 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, but there is still plenty to discover in our second, 2010, season.

The building upon which we are working 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 in 2008 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 stone warehouse was probably constructed in the first half of the 2nd century AD. Although its walls had been heavily robbed, traces of the main external walls, internal partitions, and some areas of flagstone flooring were all uncovered. We will be concentrating on more fully exposing these levels in our 2010 season. An intriguing episode of alteration to this building was also discovered, in the north-east corner of our trench, where part of the wall facing on to the interior courtyard had been dismantled, and a new flagged entranceway laid across its foundations (see picture below). Confirming the dating of this alteration is a priority for our forthcoming season, but it may be later Roman.

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. However, 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.

For more details on the 2008 season, including some of our major finds, see the excavation blog and also the interim report on the CRC website (

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

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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