The Roman fort on the ridge above Pen-llwyn overlooked the Roman road where it crossed the River Rheidol. There are no surviving earthworks and it was first recognised from the air as a series of cropmarks. Small scale trenching confirmed its identification as a Roman fort and geophysical survey has added much detail to the plan. It appears to have been established in the Flavian period and was occupied until at least AD 125 and possibly AD 140.

The fort covers approximately 2.7ha and is one of the largest in West Wales – its size probably more the result of topography than importance. The triple ditch defences, with entrances in each side, measure 185m north-east to south-west by 140m, and have distinctive rounded corners. They are backed by a rampart of turf packed with gravel and clay.

There was also an outer ditched circuit some 25-35m beyond the triple ditches on the north-west and south-east sides and running down to the river terrace some 250m distant on the south-west side. The way the fort has been fitted into the site’s natural topography is interesting. The highest part is the rear, north-east division and the headquarters building occupied a sheltered hollow at the centre of the fort. The ramparts crown steep slopes on the north-east and south-west sides.

The defences at the western corner-angle were sectioned in 1976; the outermost ditch was not dug, the median ditch was V-shaped, and measured 8½ ft. wide by 4½ ft. deep (c.2.6 x 1.4 m), separated from the outer ditch by a gap of about 10 ft (3 m) and from the inner by a gap of 11 ft. (c.3.3 m), the inner ditch was also V-shaped, 9½ ft. wide and 5½ ft. deep (c.2.9 x 1.7 m). The rampart, between 13½ and 16½ ft. broad (c.4.1-5.0 m), was perhaps revetted at the rear with timber. A field-oven and a pit of food-waste was covered by the rampart-spread, which had been deliberately slighted into the inner ditch. Scarce pottery finds seem to indicate a brief occupation during the Flavian-Hadrianic period.

References for Pen Llwyn

  • Air Reconnaissance in Britain, 1973-76 by J.K. St. Joseph in J.R.S. lxvii (1977) pp.152-4 & figs. 16/17;
  • Britannia ix (1978) p.408;

Map References for Pen Llwyn

NGRef: SN6580 OSMap: LR135

OS National Grid Reference: SN650806
Dimensions: c.600 x 515 ft (c.183 x 157 m)
Area: c.7 acres (c.2.87 ha)

Roman Roads near Pen Llwyn

N (6) to Erglodd (Powys) Probable road: SSE (5) to Trawsgoed (Dyfed)

Sites near Pen-Llwyn Roman Fort