The wall of a Roman station, between the gateways, was often flanked by a series of towers, each projecting from the wall in the form of a semicircle or rather more than a semicircle. This was the case in some of the large Gallo-Roman cities, like Autun.[14] While the rounded form of these towers made them difficult to undermine or batter down, their summits served as standing-ground for the large [ballistae] or catapults, from which javelins or stones could be hurled upon the attacking force. Their projection at regular intervals made it possible for the defenders to command the whole line of wall between each pair of towers; so that the besiegers’ attack would necessarily be concentrated upon the towers themselves. At Pevensey ([16]), where the enclosure of the station is almost oval, and not, as usual, rectangular, in shape, there are remains of twelve solid round towers, including those which flank the south-western gateway. At Burgh Castle there are four towers in the east wall, two of which are angle-towers.[15] Owing to the scarcity of good building stone in the district, the walls at Burgh Castle are unfaced, and are built of flint with bonding courses of tiles; only the upper portions of the towers were bonded into the walls. A bed of concrete, with a platform of oak planks above, formed the foundation of the towers.[16] The angles of the wall of Roman York were strengthened by large polygonal towers. A large portion of one of these, a magnificent example of Roman masonry, remains; it formed the north-western angle of the city, and was hollow, with an internal as well as an external projection (17). No outward projections appear to occur upon the Roman wall or in the walls of its stations. The “mile-castles,” as already noted, are built against the inner side of the wall. At Cilurnum ([13]) and Borcovicus there are foundations of square towers against and inside the containing walls, while the angles of the stations are simply rounded off. The western part of the north wall of Borcovicus has also been doubled in thickness, apparently to give a safe foundation for a large catapult planted on the top of the wall. The thickening was accomplished, at a date later than the original building, by constructing an inner wall, and filling up the space between this and the outer rampart with clay. At Cilurnum, which appears to have been in existence before the great frontier wall was made, the original east and west gateways were left on the north side of the wall, which intersects the station. As they were thus insufficiently protected, they were filled up solid with masses of rubble, and were probably used as platforms for catapults,[17] smaller gateways being made on the south side of the wall.
York; Multangular Tower
Borcovicus; Praetorium
In the interior of the station, as at Lincoln, York, and Borcovicus, the main street, or via principalis, led directly from the north to the south gate.[18] The centre of the station, west of the via principalis, was occupied by the praetorium, the headquarters of the commander of the legion, answering to the space where, in a temporary camp, the tents of the general and his staff were pitched. As we have seen, the place of the praetorium was taken in commercial towns by the forum. The praetorium at Borcovicus consisted of two rectangular courts, open to the sky in the centre. The outer court, with its main entrance facing the eastern street or via praetoria, was surrounded on three sides by a colonnade. A doorway, immediately opposite the main entrance, opened into the eastern colonnade of the inner court. This had no northern or southern colonnades, but had doorways to north and south: its western side was occupied by a line of five rectangular chambers, the central one of which was the chapel where the standards, with the other sacred treasures belonging to the cohort,[19] were kept. The praetorium faced the eastern street of the station, which led to the east gate or porta praetoria. The gate at the end of the western street was called porta decumana.[20] The remaining buildings of the station consisted of straight blocks, intersected by lanes: the majority of these buildings would be used as barracks. It should be noted that, in the planning of a Roman station or walled town, the praetorium or forum was taken as the central point: the via principalis, in order to run clear from gate to gate, was thus on one side of an axis of the rectangle, and the north and south gates[21] were not in the centre of their respective walls.
It is clear that, as time went on and the power of Rome in Britain grew weaker, the defensive character of the great wall and that of the stations which it connected were emphasised at the expense of their character as bases of active warfare. But it must be repeated that Roman stations in Britain were not planned to form impregnable shelters for communities mainly pastoral. They were centres for bodies of fighting men, linked to each other by a splendid system of roads. The Roman station at Dorchester, the lines of which are so well preserved to-day, was founded, not within the ramparts of Maiden Castle or Poundbury, but on the lower slopes near the passage of the Frome. The single rampart and single ditch of a Roman town were almost invariable. Free egress as well as entrance, provisions for attack as well as defence, were necessary; and, with these objects in view, immense earthen defences, such as those of Maiden Castle, would be cumbersome. Bodies of Roman troops, as at Lincoln or Colchester, occasionally occupied part of the enceinte of a British settlement; but it is very rarely that, as in the case of Old Sarum, we find a British hill fort which also probably served as a Roman station. In this instance, the occupation of the fort was due, doubtless, to its neighbourhood to the military road: the road would not have been brought out of its way to include the fort in its course. Roman stations, although they differed in size, were small and compact, when contrasted with the large and straggling areas occupied by the British settlers. Suburbs naturally grew up outside their walls, and sometimes, although not very often, the walled enclosure was extended to include a growing outer district. This is supposed by many antiquaries to have happened at Lincoln, where the original Roman station occupied the summit of the hill north of the great bend of the Witham, which here turns from its northerly course due eastward. After the city of Lincoln had settled down to civil life, practically the whole slope of the hill south of the first enceinte was included within the city and encircled by a wall. Part of the east wall of this later enclosure is still visible: the Stonebow, the medieval south gate of the city, about a hundred yards from the river and the bridge, appears to be on the site of the later south gateway of Roman Lincoln.[22]