ollowing the arrival of the 20th Legion Valeria Victrix in around 87 AD there began a period of substantial building and refurbishment at the Chester fortress which was set to last for the next two hundred years or more. The most obvious improvement was the replacement of the outer wooden defensive palisade with a much more substantial sandstone wall. This rich red sandstone was quarried from outcrops on both sides of the river, including the area of what is now Edgar’s Field in Handbridge and from the northern bank of the river in the area now covered by the modern day Nun’s Field. 
The front of the original earthen rampart was thought to have been cut back to produce a vertical face against which the sandstone wall could be set. It was laid upon a foundation trench cut into the natural bed-rock and then filled with crushed rubble, some 18 inches deep and 6 feet wide, which would help carry the stones enormous weight. The outer face of the wall rose to a height of about 22 feet from ground level and was made up of individual blocks, each 4 feet in length. This outer wall was supported to its rear by crushed rubble packed directly between it and the existing earth and timber rampart. This rear section also carried the walkway, along which Roman sentries patrolled and was thought to have stood at a height of 16 feet. The remaining 6 feet was made up of a defensive parapet, behind which the defenders could monitor the wider area and the civilian settlement which had grown up immediately outside of the fortress. Fronting the perimeter of the fortress was the Fossae, the defensive ditches which surrounded each Roman settlement or camp and which were reported to have been V-shaped constructions. The average dimension for such ditches was 10 feet deep and 20 feet wide, with the spoil being used to construct the associated defensive rampart which stood at its back. The number of ditches depended on both the local conditions and geology and the distance of these ditches from the defensive palisade was determined by the calculated throwing distance for spears and ballistae bolts, etc.
At each corner of the fortress and along the full length of its defensive walls, rectangular sandstone towers were erected at regular intervals of approximately 200 feet. These were built at the same time as the wall itself and were thought to be around 22 feet wide and have defensive walls some 4 feet thick at the base. One or two of these towers are reported to have been used as platforms for Ballistae or large catapults which were the Roman artillery of the time. Of the 22 towers which it has been suggested lined the walls of the fortress, only 6 of them have subsequently been located, as well as the remains of one of the corner towers which now lies below the much later King Charles’ Tower, which is sited near Deanery Field.
Set into each of the four walls was a gateway, of which only two are apparent today. The eastern gate was known to have stood approximately on the site of its later medieval and modern day replacement, but was substantially different to the gateway that we see today. Early illustrations (left) show it as a pair of arched gateways through which military and civilian traffic would have flowed and which was flanked on either side by a stone built guardroom.
The northern gate of the fortress was also sited near to its present day location and was reported to have been flanked by a pair of stone built guard towers. Construction of the present gateway around 1810 revealed the foundations of its Roman predecessor and excavations in the early 1970's suggested that the medieval and modern day replacements may actually have lain well in front of the original Roman defences. It was impossible to completely verify this though, due to the presence of other buildings located nearby which inhibited more extensive investigations. The southern gate was known to have been located at the junction between present day Bridge Street and Lower Bridge Street, on the site of the modern day Chester Heritage Centre, which was formerly Saint Michael’s Church. Excavations in 1908 were said to have partly revealed the foundations of this missing gateway, but little more than that is known. Finally, it is thought that the western gate was located at the junction of what is today Watergate and Nicholas Streets, with its foundations lying below what was the Holy Trinity Church and which now serves as the Guild Hall.
Immediately behind the defensive stone wall of the fortress was an open area called the Intervallum, which housed the circular legionary ovens which backed onto the rear of the walls earthen ramparts. In addition to the ovens there was a line of long narrow buildings, each 24 feet deep and 70 feet long that were constructed along each of the fortress walls and thought to have been used as store rooms, kitchens or possibly trade workshops.
Where tools, weapons or other manufactured items were required by the Legion, their garrison workshops or Fabrica would often produce such items, as and when they were required. These workshops were generally manned by skilled Blacksmiths, Carpenters, Masons, etc who were often drawn from the ranks of the Legion itself, but possessed the additional specialist skills required to meet its everyday needs.
The Intervallum was the gap or physical space between the settlements outer defenses and the internal living accommodations which housed the Legionary troops. Often this area could be as little as 60 feet wide, but could be up to 200 feet, depending on the overall size of the Roman station itself. This area or space allowed for free and easy access to the defensive walls and reduced the potential for burning projectiles to be launched at either living quarters or important Legionary buildings.
The Via Sagularis roadway which ran behind the full length of the fortresses defences was thought to have been around 30 feet wide and bordered on either side by three foot wide sidewalks. Both sides of the road were defined with sandstone kerbstones laid vertically and a drainage system which ran along its full length. This particular feature was thought to have been used almost exclusively for the movement of military traffic, including patrols and materials within the fortress and thus avoiding the need to move them around the centre of the base.
Running through the centre of the Intervallum and along the full length of the defenses the Via Sagularis also contained the main drains which drew rain water from the centre of the camp and from the roofs of buildings which backed onto the defensive wall. Typically running down a slight gradient, this accumulated water was then used to flush the settlements latrines which were generally located at the lowest point of the camp.
The routes of the main Roman roads that lay within the confines of the fortress are still fairly evident in the city today. Eastgate Street (right) and Watergate Street clearly mark the line of the Via Principalis, which close to its western end meets the Via Decumana or Northgate Street, at the site of the present day High Cross. Bridge Street or the Via Praetoria, on its original line, would have run northward to join Northgate Street and intersecting with the other two roads around the junction of the Roman headquarters building, the Principia, which lay at the southern end of Northgate Street and which today lies beneath the much later St Peter’s Church.
Today’s obvious lack of a direct north-south alignment between Northgate Street and Bridge Street is almost certainly due to later redevelopment and construction in both the Bridge Street and lower Northgate Street areas. If, as has been reported, the southern gate of the fortress now lies below the site of the modern day Heritage Centre, then it seems sensible to conclude that, part if not all, of the original Roman road lies slightly to the east of its present route and below the famous Bridge Street Rows, which were constructed much at a much later date. St Peter’s church which stands on the lower western side of Northgate Street at its southern limits, close to the High Cross, has partly encroached onto the line of the former Roman road, the Via Decumana, causing an obvious narrowing of the street and suggesting an even greater lack of alignment between two roads.
The Principia or headquarters building was known to have represented the administrative and judicial centre of every Roman settlement and as their most important building was invariably sited at the junction of the Via Principalis and Via Praetoria. Excavations at Chester have clearly demonstrated the phased development of this particular building throughout the entire Roman occupancy of Chester. In the early years of the fortress the Principia was known to have been constructed of timber and much smaller in size than its later stone-built replacement. In view of this earlier first century building being of a much smaller size, it has been suggested that the earlier route of the Via Principalis was itself some 22 metres north of its present location. However, expert opinion is highly divided on this issue with many historians believing that such an idea is at best highly speculative.
The later stone building was thought to be of a much more extravagant construction and was said to have been part of a major rebuilding project undertaken during the early part of the 2nd Century. The Principia was known to have included a large open courtyard area, behind which lay the judgement hall, offices and the shrines which were dedicated to various Roman deities.
Below the level of the building and cut into the natural bedrock was a strong-room which held the Legionary pay chest and other regimental valuables. A small section of this room can be seen today, through a viewing window which was built into the south side of the Forum Shopping Centre, which itself replaced the earlier Market Hall (left). The total length of the Principia building was determined to be in excess of 300 feet and over 230 feet in width. The structure was supported by a series of massive stone columns and the south facing entrance of the building was deliberately built up with terracing to further enhance its already imposing façade. Excavations which took place in 1897 at 23 Northgate Street and those in Goss Street between 1948/9 have helped to confirm these dimensions, whilst at the same time exposing the bases of a number of the buildings massive support columns.
To both the west and the east of the Principia lay a range of barracks, of which there were many within the fortress. Throughout the whole first two centuries of occupation these legionary barracks were thought to be of a mainly timber construction, with later versions built on much more permanent stone sills. Stone barracks were eventually built, but not until the third century of occupation. With over 5000 men to house and feed, much of the fortresses space and resources would have been given over to these particular purposes. Each legion was usually comprised of ten cohorts, each of which consisted of some 480 men.
As would have been expected, these forces would have been spread around the length of the fortresses defensive walls in order to both protect and patrol the site. Also to the west of the Principia building in what is now Goss Street lay a stable block, thought to have been used by a small detachment of cavalry that were said to have been based in the fortress. In a later period of development these same buildings appear to have been altered and reused as living quarters or offices.
To the north of the Principia, in what is today the Market Hall area of Chester, there were a number of important Roman buildings which included one with a central elliptical courtyard which has continued to defy identification and explanation since it was first seen in 1939. Thought to date from around the third century, it has been suggested that this building may be entirely civilian in nature, rather than military and could have served as a theatre or as a shrine, but as yet no definitive evidence exists either way.
Immediately behind the Principia, at its northern end was the Praetorium. This building was the residence of the legionary Legate, the fortresses commander and the man who implemented both Roman planning and policy for the area and therefore the most important person residing within the base. Separated from the Principia by a road some 20 feet wide, the Praetorium was estimated to have measured over 200 feet from east to west and a similar distance from north to south. It appears to have been originally built of stone, but was continuously redeveloped over time with periods of substantial change, including widening and partitioning of various rooms and the rebuilding of internal and external entrances. A Roman altar thought to have come from within this building was unearthed in 1851 and is now held by the Grosvenor Museum.
Doubts were subsequently cast on the identification of the site as the Praetorium, in view of the apparent low level of decoration and finishing that were found during its excavation. One suggested alternative was that the building was in fact the Valetudinarium or Legionary hospital and this theory was partly supported by an altar found in 1851 which had been dedicated in Greek by a doctor called Hermogenes. The finding of a second altar during the excavations of 1967/8 and dedicated to another doctor called Antiochus seemed to further strengthen the hospital theory. However, those that believed the site to be the Praetorium and not the legionary hospital, pointed to the fact that this altar had almost certainly been moved from its original position and that the building itself did not correspond to known hospital plans taken from other fortresses. It was not unreasonable, in their view that the doctors would have lived within the Legate’s residence and would have dedicated the altars within that building.
Further west of the Principia and Praetorium, lying just within the western defences were more barracks and workshops and outside of the wall lay the legionary cemetery where the Romans buried their dead comrades. Back inside the walls and north of the elliptical building, towards the northern defences of the fortress were a series of buildings, including a water tank, workshops and legionary barracks. Much of this northwest quadrant of the city has been the subject of massive redevelopment during the twentieth century, particularly in the late 1960s and early 1970s. Evidence of many of these major Roman buildings was completely removed during construction of the Forum shopping centre and its associated underground parking areas. The Roman archaeology that does remain intact does so only because it has been protected by other later structures, such as pubs, private housing and the city’s imposing Town Hall (illustrated right by Louise Raynor).The north eastern quadrant of the city has been much less developed than its western counterpart, perhaps as a direct result of its later history as a religious precinct of Chester’s Cathedral which has stood, in one form or another for well over a thousand years. Apart from infrequent excavations that have allowed identification of Roman ovens, workshops and sections of defensive ramparts the area remains largely undiscovered.
In 1868, restoration work on the Lady Chapel within the Cathedral revealed a Roman concrete floor, a drain and traces of a road which ran diagonally under the south-eastern buttress some 9 feet below present ground level. As little or no substantial archaeological work is anticipated within the immediate cathedral grounds, it is virtually impossible to know exactly what Roman architecture remains there and perhaps never will.
Almost the opposite is true of the south east quadrant of the Roman fortress in the area now almost fully obscured by the later Grosvenor Shopping Precinct and its underground car parking and delivery bay system. Within this particular area of the fortress which was known as the Praetentura lay a Basilica, a large aisled hall to the south of which lay rooms with tessellated floors and heated by a Hypocaust. Further observations of the site proved that this was the location for the main legionary bath houses within the fortress and reflected to some degree the very centre of fortress life and leisure time. The northern third of the complex was thought to be the covered exercise hall, called the Palaestra. Generally, such halls were open-roofed, but the cold climate probably caused the hall in Chester to be covered. In the south east corner of the site it was speculated that a large water tank had stood, supplying water to the complex’s baths, saunas and latrines.
In 1863 two fragments of inscribed marble were found, which later study proved to be from the time of the Emperor Vespasian and dating the bath house to around 79 AD. Later archaeological evidence also proved that the bath house had been constructed during the first phase of occupation at the fortress and that both it and the exercise hall were both in use up until the third century. The baths part of the complex was estimated to measure some 275 feet along its north south alignment and was approximately 265 feet wide, making it a wholly substantial feature within the fortress and perhaps indicating its very importance.
So-far unseen sections of the complex are thought to have been located below the modern street frontages in Bridge Street, including the Natatio or swimming baths. Given the level of later development however, it is unlikely that much remains of these sections of the original Roman complex. Typically though, such a leisure centre would have included a changing area, the Apodyterium, where the bather would have got undressed and stored their clothes. They would then enter the Frigidarium, where they could initially wash themselves, before moving on to the Tepidarium where the sweating process began. Then into the Caldarium where there were hot baths, in which the bathers could immerse themselves and scrape their skin clean using a Strigil. Finally the visitor would then return to the Frigidarium in order to cool himself off before getting dressed and returning to his daily routine.
Outside of the south west corner of the fort, remains of an unknown structure which included an altar were found during later excavations. In around 1976, in the area of 