A major research, training and engagement excavation at Priory Field in Caerleon revealed unique new evidence from a store building within the legionary fortress of Isca.

Directed by Vianova’s Peter Guest and Prof. Andrew Gardner from the UCL Institute of Archaeology, the Priory Field excavation and its published report represent a number of significant firsts:

• • 1st legionary store building excavated to modern standards in the Roman Empire
  • 1st time an excavation trench at Caerleon was positioned to answer specific research questions about the interior of the fortress
  • 1st excavation in Caerleon that was open to the public, who joined in as volunteers or visited the site on a daily tour or one of our many open days
  • 1st major excavation at Caerleon in the 21st century
  • 1st publication of a major Caerleon fortress excavation since 1986

Pioneering geophysical surveys – magnetometry and resistivity – carried out in Priory Field in 2006 and 2007 had identified at least thirteen previously unknown Roman buildings, including barracks, granaries and one range of a large courtyard structure (for more about the geophysics, see the Mapping Isca project).

These belonged to Caerleon’s Roman past 1,900 years ago, when the town was the site of the legionary fortress known as Isca and the base of the Second Augustan Legion (one of only three Roman legions stationed permanently in Britain).

The Priory Field geophysical surveys have been published in 2 articles in the journal Archaeologia Cambrensis – offprints are available here and here.

Some Roman military buildings have characteristic plans reflecting the activities that took place in them (for example, granaries, barracks, baths and headquarters), but courtyard buildings are thought to have fulfilled a range of functions in legionary fortresses, including stores, hospitals and workshops.

The Priory Field example was almost square in plan and covered an area of approximately 60 m by 64 m.

Four ranges, at least two of which were subdivided into smaller rooms, enclosed the large central courtyard, around which ran a covered (probably colonnaded) portico. The main entrance appears to have been located in the centre of the southwestern range, leading out onto an extensive yard between the building and three granaries close to the fortress’s west gate.

The excavation discovered when Priory Field’s courtyard building was built, what it was for, when it ceased to be used, and what happened to it during and after the later Roman period.

This was the first occasion in Caerleon’s long archaeological history that an excavation trench had been positioned to answer specific research questions about the interior of the fortress. It was also the first time that an archaeological excavation in Caerleon had been organised and led by a university-based team and it was, therefore, the first opportunity for undergraduate and postgraduate archaeologists to gain practical fieldwork experience at this internationally important site.

Following a small evaluation season in 2007, a large trench was positioned over the courtyard building’s southwestern range, which was excavated over ten weeks in 2008 and 2010. About two-thirds of the range was investigated and the excavation recorded one of the few complete archaeological sequences for a Roman building in Caerleon.

The trench exposed the building’s main entranceway and its adjoining guard chamber, a possible stairwell, four small square rooms with beaten earth floors and white-washed plastered walls, and a length of the colonnaded portico around the courtyard.

The building’s architecture indicates that it had a utilitarian function and it served as the legion’s main store, where items that were not required by their owners were kept until they might be needed again, or moved elsewhere. Carts and other traffic passed into the building’s courtyard on robust and durable surfaces in the entranceway and courtyard, from where military equipment and other goods would have been unloaded onto the portico and into the store rooms.

The store’s very solid foundations were intended to support a considerable weight and the extra-width of the front wall’s foundations suggests that the building’s façade could have been several storeys high (the portico might have supported a balcony for the upper floors, perhaps of timber, accessed via the stairwell next to the entranceway). This was the first legionary store excavated to modern standards in the Roman Empire.

Debris from the derelict building sealed the floors of two store rooms, one of which seems to have been used to keep household and personal items, including furniture, glass bottles and jugs, as well as brooches, a finger ring and a mirror fragment, some of which might have been kept in boxes or caskets.

The floor of the second sealed store-room was littered with military finds, many of which survived in a very fragile condition (particularly the iron artefacts that had not survived well in Priory Field’s damp aerated soils). These artefacts were carefully removed and conserved, which in 38 instances involved their lifting in soil blocks that were later excavated under laboratory conditions.

Although the iron was often almost entirely mineralised, nevertheless it soon became clear that the soil blocks contained the highly fragmentary remains of at least two sets of dismantled lorica segmentata body armour that had been scattered across the room’s floor, as well as another set of scale armour and an elaborately decorated horse’s headpiece. The lorica segmentata was of the Newstead type, which had been dismantled and partially recycled by the time the roof collapsed (the armour was probably of some antiquity when this happened).

The horse’s headpiece is a very rare example of a leather chamfron covered with hundreds of round copper pins, studs and other decorative plaques, that was probably used by cavalrymen or officers for parades and official ceremonies.

The chamfron’s leather mask had long since decayed and only the copper fittings survived in a jumbled mass within the largest soil block.

It is similar to other chamfrons from Vindolanda and Newstead in northern Britain (where the leather survived in waterlogged deposits), although the Priory Field find is unique as it included panels of overlapping pins that must have glistened in the sun.

Two new buildings were constructed among the ruins of the old and partially demolished legionary store. The store’s façade seems to have remained partially standing and it was reused by at least one three room cottage-like building that had been very poorly constructed and fell down. A stone-lined pit in its central room contained numerous fills of burnt plant material, including wood charcoal, cereal grains and other seeds. Several samples were sent for radiocarbon dating, which demonstrate that this building was constructed and in use between 430 and 600. This is the first new structure at a Roman site definitively dated to the post-Roman 5th and 6th centuries from Wales (arguably, from Britain) and it has an important story to tell about life in the old legionary fortress after the ending of Britannia, c. 410.

The Priory Field excavation was also a training and engagement project and 115 students and volunteers worked on site during the two seasons (many other students also contributed to the post-excavation work, particularly on the finds conservation).

Almost 7,000 people visited the excavation, either joining daily tours or attending one of the Open Days when visitors could take part in a range of archaeological activities, such as wet and dry sieving, making pots, tasting Roman cookery, a colouring competition, or trying on a Roman helmet. This was the first time a research excavation in Wales had opened its doors to the general public in this way, and it proved to be extremely popular with people from Caerleon and far beyond.

The excavation report is available as a paperback volume or Open Access PDF eBook from Archaeopress.

The excavation report is the culmination of the Priory Field research project. A total of 138 people worked on site at Priory Field, including academic archaeologists, commercial field archaeologists, student archaeologists and volunteers in various guises.

The report includes contributions from dozens of conservators, archaeological scientists, finds specialists, illustrators and photographers.

Priory Field is owned by the Welsh Government and managed by Cadw. Cadw also provided substantial financial assistance at all stages of the project,