also known as Cwm-Aran & Gemaron

The remains of the castle are remotely situated - north of the A488 (Llandrindod Wells to Knighton) but south of the B4356 (Presteigne to Llanbister). It is 3 miles south-west of Llanbister Road station in Powys.

Article by Paul Remfry
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Photo: © Crown Copyright: Royal Commission on Ancient and Historical Monuments of Wales

It seems likely that the castle was founded during the Mortimer conquest of the cantref* of Maelienydd in the late eleventh century. The Mortimers were exiled during the reign of King Henry I (1100-35) and the castle passed to the powerful royal confidant, Pain FitzJohn. During 1134 the Welsh revolted and 'Cans' castle was one of the fortresses of FitzJohn that was destroyed. This was probably Cymaron. In 1144 Hugh Mortimer (d1181) ‘repaired Cymaron castle and a second time subjugated Maelienydd’. Within ten years the castle was retaken by the Welsh and remained in the hands of the local princes for the next 25 years. On 22 September 1179 Roger Mortimer (d1214), the son of Hugh, murdered the castle’s lord, Prince Cadwallon ap Madog. Immediately King Henry II seized the castle due to the great debts Cadwallon owed the Crown. He also arrested Roger Mortimer and imprisoned him for two years. In 1182 Cadwallon’s sons seized back the castle much to the annoyance of the king. In 1195 King Richard I gave Roger Mortimer an army to reconquer Maelienydd as well as £20 towards refortifying Cymaron castle. Roger Mortimer finally died in 1214 and the next year Prince Llywelyn the Great swept through Maelienydd destroying ‘Kamhawn’ castle once more. This appears to have marked the end of the castle’s military history, although the Mortimers later built a court house here before 1297, though whether this was a defensive structure or not is open to question. Cymaron manor records still exist for the years 1356 to 1360.


Strategically Cymaron castle lies on the River Aran which gives the fortress its name. It would also appear to have been the caput**, or in Welsh the llys, of Rhiwallt commote***. As such it was a very important castle. Tactically the castle is badly sited. It is set on the junction of the River Aran and a small stream. It probably commands an ancient crossing of the river, but the site is badly overlooked by high ground to the south and west. A motte, either as a lookout or an outpost - Colwyn castle in Elfael has similar supporting mottes - stands on the high ground to the south-east of the castle and river. A further mound which appears to be natural lies up the slope from the castle motte to the south-west. If both these ‘mottes’ were fortified it would have somewhat alleviated the bad positioning of the castle.

Photo: Gregg Archer

The castle consists of an irregular motte still protected by deep ditches and ramparts. A bailey with massive ramparts and ditches lies to the east and a further less-well-defended bailey beyond that. In the eastern half of the inner bailey are two apparently fairly modern buildings, built of the local rubble, but we could find no trace of any courthouse which once stood at the site.

*A Cantref (Welsh pronunciation: [ˈkaːntrɛ(v)]) was a medievalWelsh land division, particularly important in the administration of Welsh law.
**The Latin word caput, meaning literally "head"
***A commote was a secular division of land in medieval Wales
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