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Dinerth Castle, Castell Allt Craig Arth

Also known as, or recorded in historical documents as;
Hero; Monachty; Dinierth; Dineirth; Llanrhystid

In the community of Dyffryn Arth.
In the historic county of Cardiganshire.
Modern authority of Ceredigion.
Preserved county of Dyfed.

OS Map Grid Reference: SN495624
Latitude 52.23885° Longitude -4.20626°

Dinerth Castle, Castell Allt Craig Arth has been described as a certain Timber Castle.

There are earthwork remains.

This site is a scheduled monument protected by law.


A complex earthwork castle occupying a steep-sided narrow promontory above the confluence of the Arth and Erthig streams. The castle covers an area of some 90m east-west by at most 24m and opens onto a small plain fringed by wooded slopes on the east. The entrance negotiates a swathe of double ramparts and ditches set across the neck of the promontory, the inner rampart rising some 7.2m from the base of its ditch. There are two adjacent steep-sided flat-topped mounds on the north side of the promontory. The first faces the entrance across a ditch. It is 7.2m high and some 30m in diameter, with a near rectangular summit some 10m across, presumably the site of a tower. The second mound is rather smaller, some 5.4m high, and lacks a ditch, but is otherwise similar and presumably also supported a tower. The remainder of the earthworks comprise a series of ledges, or platforms about the south side of the mounds. These are probably the site of the buildings of the castle court, including a hall. The site is identified with a documented castle, first recorded (as destroyed) in 1137, whose demise is noted in 1207-8. (Coflein)

Motte and bailey on a promontory between the Arth and its tributary, the Nant Erthig. There could well have been a prehistoric defence structure here that was adapted in medieval times. There is a strong ditch and linear ridge defence on the eastern side, whilst all other sides fall into steep ravines. There seem to be three separate mounds within the site which covers about 3 ha. Dinerth was originally built by the de Clare family around 1110. It has had an extremely chequered history - razed by Gruffydd ap Rees in 1116, and again by Owain of Gwynedd in 1136. It was occupied by Hywel in 1143, and by Cadwaladr in the following year. In 1158 it became part of the lands ceded by the Normans to Earl Roger of Hereford. It was destroyed yet again by Lord Rhys in 1164, and came into the possession of Maelgwyn who lost it to his brother, but recovered it in 1199. It is thought to have been completely destroyed by Maelgwyn in 1202. (Richard Hartnup)

This is a strong confluence site, a type very common in Cardiganshire. The small river Arth, curving from S. to W., runs for about 200 yards parallel to the Erthyg brook before the two meet. Both have deep and steep valleys, that of the Arth being exceptionally formidable, with a headlong scarp about 60 ft. high-almost a cliff. The narrow projecting ridge (about 30 yards across on the top) is the site of the castle. The motte and bailey stand at the root or base of the ridge, away from the falling ground on the point, which may have formed some kind of rear bailey or basecourt, cut off from the castle proper by a seven-foot scarp across the spine of rock, about 180 ft. from the point of the ridge. A little way behind comes the ditch of the motte itself. The motte is stony and largely natural it is only ditched on the W., against the high spine of the ridge, over which it has little command. It stands against the fearsome obstacle on the N. on the E. and S. is the bailey. The modern track passes along the S. side, and has to some extent obscured the plan. The motte is very narrow, with its axis along the ridge its summit is bumpy, with a decided ledge around its rim, which suggests some stone construction on it. The bailey is very short, with formidable twin banks and ditches across the level isthmus. The entrance is at the N. end, and probably always was. This was originally a Clare castle, destroyed in 1137, rebuilt in 1159, and finally dismantled, like Ystrad Meurig, in 1207. (King, 1956)
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Data >
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This record last updated 02/07/2016 17:58:40