The ditched and banked sub-circular enclosure at Carreg-y-Bwci measures 10-12m in diameter, having a recumbent monolith, about 5.0m by 2.0m, resting across and immediately within the south-west facing entrance. Set close to the line of the suggested Roman road from Llanio to Pumsaint (NPRN 303528), the site, previously considered to be a prehistoric monument (Daniel 1950, 216), has been identified as a Roman tower emplacement (Davies 1986). As such it is similar to examples such as Roundlaw in Perthshire and Easton in Cumbria and would have featured a four- or six-post watch-tower when in use.

Disturbances within the monument (around a fire-site, possibly associated with neo-pagan observances), have exposed a clay layer overlain by stones, possibly the features noted by Thomas (1879, 58-9), appearing to form some kind of paving. The bank appears to have much stone in its make-up.

Other possible Roman tower sites in the region are Pant-y-Rhedin (NPRN 303893), Waun-wen (NPRN 310385) and Erryd (NPRN 310463). A recently-identified Roman fortlet lies just to the south (NPRN 309063).

Sources: Thomas 1879 (AC 4th series 10), 55-62;
Daniel 1950 'the Prehistoric Chamber tombs of England & Wales';
Davies 1986 (AC 135), 147-53;
1994 (in Cardigan. County Hist. I), 307-8.

J.Wiles, RCAHMW 29 October 2004, and T. Driver, RCAHMW, 2 September 2009.