This possible fortlet lies at an altitude of 305m OD on Gibbet Hill, 2 kms south of Llanfair Caereinion. Known locally as Y Gaer, it lies on the ridge south of the River Banwy, 12 kms north-west of Forden Gaer. No Roman road has yet been shown to follow the Banwy valley, but it remains a possibility. The site, which measures 50.9 by 46.3m, encloses an area of 0.24 hectares (0.59 acres). Its rampart and ditch have never been ploughed. E. T. Pickmere carried out an excavation in 1857, but it seems that Roman pottery and a tile supposedly found here really came from another site.

Excavation in 1962 showed that the site was unfinished. The turf-faced rampart was 3.4m wide, fronted by a ditch 2.5m wide and 1m deep; there was a single entrance, 3.4m wide, in the east side. Nothing was found in the interior; no road had been laid and no gate built. The post-holes for the rampart walk had been filled in without posts being inserted. Outside the fortlet to the east lay a low mound of burnt material 22m across.

If the site is Roman in date, then signalling is the only feasible purpose, but the plans seem not to have been completed. The mound of burnt soil and charcoal is most likely to represent clearance of the site before construction. In the absence of finds from the later excavation, the Roman date must be regarded as unproven.

Sources: RCAHMW&M Montgomeryshire Inventory (1911), 83-4 No. 419, fig 26
Putnam in Montgomeryshire Collections 58 (1964), 21-6
Jarrett 'The Roman Frontier in Wales' second edition (1969), 142-3

T.G. Driver, RCAHMW, December 2009.