|Margary #621: N (17) to Castell Collen (Powys)
Margary #621: SSE (5) to Y Gaer (Brecon Gaer, Powys)
|SO024371||c.62 x 62 ft
(c.19 x 19 m)
This site lies along the line of Ivan Margary's postulated extension of the Cardiff-Brecon Gaer road northwards (Margary #621), at the point where the road left the valley of the Afon Honddu and made off, almost due north, across the moors towards Castell Collen. The encampment is very small, measuring only 62 feet square across the rampart crests, with a centrally placed entrance gateway 10 feet wide in the southern defences. The preservation of the site is remarkable, the rampart existing to a height of about 6 feet (c.1.8 m) above the general lie of the land and over 10 feet (c.3 m) above the bottom of its single encircling ditch.
The site is comparable to many of the late-Flavian works in south-east Scotland and may yet prove to be a late-1st century signal-tower or guard-outpost, but the attribution of a Roman date to Castell Madoc is not supported by any physical evidence other than the style of its defences. Because of this, perhaps, the site has never been included on the maps of Roman Britain produced by the Ordnance Survey.