Type: Fort, Practice Work, Industry
|Road: NNE (13) to Castell Collen (Powys)
SW (15) to Llandovery (Llandovery, Dyfed)
Postulated Road: ENE (5.5) to Penmincae
|SN924501||550 x c.370 ft
(167 x c.113 m)
Almost the entire defensive circuit of this fort may still be traced in fields surrounding the modern farm. The earthworks define a trapezoidal area measuring about 550 feet (c.167 m) along its long axis from north-east to south-west, with visible gateways in the centre of the north-east rampart and in the north-west side about one-third of the way from the south-western end. The north-east side is about 120 yards (c.110 m) in length, while the south-west defences, now mostly obliterated by a Norman Motte sitting squarely astride them, are around 128 yards (c.117 m) long. The main ramparts enclose an area of around 4¼ acres (c.1.77 ha), which is enough to have housed a Cohors Quingenaria Equitata, a mixed regiment of both infantry and cavalry with a nominal complement of 500 men. There are traces of an annexe attached to the eastern side of the north-eastern rampart, and traces of a second defensive ditch at the southern corner angle.
The main enclosure is sub-divided by an internal scarp running from a point in the north-west rampart about 200 feet (c.61 m) SW of the northern corner angle to a point in the opposite (south-east) rampart about 175 feet (c.54 m) SW of the east corner-angle. This embankment, which sports a gateway roughly midway along its length, reduces the fort to an almost square outline with an internal area of about 3¼ acres (c.1.32 ha). This reduction in occupation area points either to a reduction in the size of the garrison due to retirement or secondment, or to a change in the type of regiment housed, for example a part-mounted regiment being replaced by a pure infantry regiment; the excess area being that taken up by the original unit's horses.
The ramparts at the north-east corner are reported to have measured 12 feet (c.3.66 m) high in 1958, but repeated ploughing had reduced the main rampart to an average of a little under 5 feet (c.1.5 m) by 1985.
The Roman road running south-west from Castell Collen crossed the Afon Camarch some 490 yards (c.450 m) to the north of the fort, turning due south upon crossing the stream and passing just 110 yards (c.100 m) outside the fort's western corner-angle before continuing on to Llandovery. The two supposed Roman military 'practice works' at Caerau both lie on the opposite (west) side of this road from the fort, one around 215 yards (c.195 m) to the immediate west, the other about 340 yards (c.310 m) to the south-west. The western work is rectangular in plan, measuring about 160 by 125 feet, and covering an area of just under ½-acre (c.49 x 38 m; c.0.18 ha), the smaller, south-westerly work is square in outline, measuring about 115 feet on each side, an area of just over ¼-acre (c.35 x 35 m; c.0.12 ha). There is also a large temporary marching camp only 450 yards (c.410 m) outside the fort's north-western defences at Beulah (SN9150).