Roman Exeter — known in antiquity as Isca Dumnoniorum — was one of the most strategically significant urban centres in Roman Britain. It began as a legionary fortress built for the Second Augustan Legion and was later transformed into a fully functioning Roman city, complete with monumental public buildings, a street grid, defensive walls and a forum. As the most westerly civitas capital in Roman Britain, Exeter represents a remarkable case study in how Rome converted a military installation into a thriving civilian town.
The Legionary Fortress That Came First
Before Exeter was a city, it was a military base. The Second Augustan Legion — Legio II Augusta — established their fortress at the site around AD 55–60, during the westward push of Roman conquest into the territory of the Dumnonii, the Celtic tribe who controlled what is now Devon and Cornwall.
The fortress followed the standard playing-card layout of a Roman legionary camp: rectangular, covering approximately 42 acres, with a regular internal street grid, a principia (headquarters building), a praetorium (commanding officer's residence), granaries, barracks and — crucially — a substantial legionary bath house. Archaeology has confirmed the fortress was positioned on a natural plateau above the River Exe, giving the legion both a defensible position and access to a reliable water source.
The legion did not stay indefinitely. Around AD 75, the Second Augustan Legion was transferred to Caerleon in South Wales — Isca Silurum — where they would remain as the permanent garrison for the province's western frontier. Their departure from Exeter left behind an extraordinary infrastructure.
Converting a Fortress into a Roman City
What happened at Exeter after the legion left is one of the more instructive episodes in Romano-British urban history. Rather than abandoning the site, Roman administrators converted it into the civitas capital of the Dumnonii — the administrative hub from which the tribe's territory would be governed under Roman oversight.
This process involved systematically dismantling or repurposing military structures and replacing them with civilian equivalents. The street grid from the fortress was retained and extended. A forum-basilica complex was constructed, providing the town with a commercial marketplace and a great hall for legal and administrative functions. Public inscriptions and architectural evidence suggest this was a deliberate, state-sponsored programme of urban development — Rome quite literally building a city on the bones of a barracks.
The civilian settlement that emerged was formally known as Isca Dumnoniorum, distinguishing it from the legionary base at Caerleon. It covered a larger area than the original fortress and eventually received a stone defensive circuit — the Roman city walls — sections of which are still visible in Exeter today, embedded within or beneath the medieval walls that followed much the same line.
The Roman Baths: Exeter's Most Remarkable Survival
Of everything the Romans built at Exeter, the most physically impressive survival is the legionary bath house — later converted into the public baths of the civilian town. This repurposing is itself historically significant: the bathing complex the legion built for the exclusive use of soldiers became, after AD 75, a public amenity serving the Dumnonian civilian population.
Excavations beneath the Cathedral Close have revealed the substantial remains of this structure, including some of the largest surviving sections of Roman masonry in south-west England. The baths were enormous by the standards of any British town. The main hall alone dwarfs comparable structures found elsewhere in civilian civitates, a direct consequence of the complex having been designed originally to serve an entire legion — somewhere in the region of 5,000 men.
The scale of these baths is thought to reflect the ambitions of the new civitas administration. Rather than demolish a perfectly serviceable and impressively monumental structure, they adapted it, signalling to the Dumnonii — and to visiting traders, officials and travellers — that Isca Dumnoniorum was a place of consequence.
Exeter's Place in Roman Britain
As the most westerly civitas capital in Roman Britain, Exeter occupied an unusual position within the province. To its west lay territory that was administered but never fully urbanised in the Roman manner — the Cornish peninsula remained largely rural and tribal throughout the Roman period. Exeter was, in effect, the end of the Roman urban world in Britain.
This western edge position shaped both its character and its archaeology. The town sat at the junction of major road networks connecting it to the rest of Britannia — roads heading north-east toward Bath (Aquae Sulis) and beyond, and south-east toward Dorchester (Durnovaria), the civitas capital of the Durotriges. Exeter's forum, walls and baths were not merely civic luxuries; they were statements of Roman authority at the empire's Atlantic periphery.
Archaeological finds from the city and its immediate hinterland reflect this complexity — military equipment from the legionary phase, high-status civilian objects from the town's mature period, and evidence of continued activity well into the late Roman centuries, suggesting Exeter retained its administrative importance even as the wider empire contracted.
Researching Roman Sites and Their Hinterlands
For metal detectorists working in Devon and the surrounding counties, the Roman landscape around Exeter repays careful research. The road network radiating from Isca Dumnoniorum passed through farmland and countryside that has seen relatively little modern disturbance in places, and the villa estates, roadside settlements and temples that served the civitas capital remain incompletely mapped.
Understanding what was where — and what might survive — requires cross-referencing historical sources, archaeological records, land-use histories and site-specific documentation. This is not straightforward work. The records are extensive, spread across multiple archives and databases, and interpreting what they mean for any specific field or parish demands both specialist knowledge and considerable time.
Aubrey Research automates this process, producing structured historical research reports for any location in Britain. A sample report shows the depth of information typically returned. If you want to understand what lies beneath the fields around a Roman town like Exeter, the research tool is the practical starting point.
Frequently Asked Questions
What does Isca Dumnoniorum mean? Isca is a Brittonic word for water or river — the same root that gives us the River Exe and the River Usk. Dumnoniorum means "of the Dumnonii," the Celtic tribe of the south-west. The name therefore means roughly "the river settlement of the Dumnonii," distinguishing it from Isca Silurum (Caerleon), which belonged to the territory of the Silures.
When did the Romans leave Exeter? The Second Augustan Legion left Exeter around AD 75 to relocate to Caerleon. The civilian town they left behind continued to function as a Roman city for several centuries, with occupation evidence extending into the late 4th and early 5th centuries AD.
What Roman remains can be seen in Exeter today? The most significant visible remains are sections of the Roman city wall (incorporated into the later medieval defences), and the preserved remains of the Roman bath house beneath the Cathedral Close. The Royal Albert Memorial Museum in Exeter also holds a substantial collection of Roman finds from the city and region.
Why was Exeter the most westerly Roman civitas capital? Roman urban administration followed the pattern of existing tribal territories. The Dumnonii occupied Devon and Cornwall, and Exeter was the natural centre of their territory. Further west, the landscape was more sparsely populated and less amenable to the kind of urban infrastructure Rome typically imposed on conquered peoples — making Exeter the permanent western limit of the civitas system in Britain.