The fort at Llwyn-y-Brain is visible from the air as a round-angled rectangular cropmark enclosure, 246m WSW-ENE by 178m with an annex on the western side. It was first noted by J.K. St Joseph in 1955-7 and it is sited on a low hill on the north bank of the River Severn. Exceptional conditions for aerial photography revealed details of the site in August 2006 and an extensive geophysical survey in 2007 suggested foundation trenches for timber buildings, roadside drains and a series of ovens, hearths and pits on the western side of the north gate. Little dating evidence has been recovered apart from a few sherds collected during field walking. It is unlikely to be pre-Flavian in date, but it is presumed to preceed the Flavian fort at Caersws, though the interval between the two forts is unknown. The Roman road system in the area ignore the site.

Sources: St Joseph 1958 (JRS48), 86-101;
Jarrett 1969 'Roman Frontier in Wales' 2nd ed., 66 fig 29;
Dawson 1983 (AW23), 50.
Jones 1996 (AW36), 79.

J.Wiles, RCAHMW, 18 August 2004