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Tomen y Mur, Maentwrog

Also known as, or recorded in historical documents as;
Mur Castell; Heririmons

In the community of Maentwrog.
In the historic county of Merioneth.
Modern authority of Gwynedd.
Preserved county of Gwynedd.

OS Map Grid Reference: SH70543866
Latitude 52.92980° Longitude -3.92730°

Tomen y Mur, Maentwrog has been described as a certain Timber Castle, and also as a Masonry Castle although is doubtful that it was such, and also as a probable Palace.

There are earthwork remains.

This site is a scheduled monument protected by law.


The medieval motte or castle mound at Tomen-y-Mur ('the mound on the wall'), is a dramatically mutilated mound set over the north-west gate of the reduced Roman fort (NPRN 95476). It is identified as a medieval castle mound, although documentary evidence is lacking. References to the site seem to relate to the fort in general. The earlier name was Mur Castell. This may have been the site of a medieval llys or princely court. The tomen is a near-circular steep-sided mound, about 36m in diameter and 6.5m high. The 16m diameter summit has been disturbed in the past. An embanked ditch runs around the foot of the mound. It is built of stone blocks taken from the fort ruins and may conceal a standing Roman gate. The Roman fort circuit appears to have been refortified. Pennant observed ruins of a wall atop the bank in the late eighteenth century. There are traces of post-Roman settlement features to the north-west of the fort (NPRN 89391). (Coflein–John Wiles 11.07.07; T. Driver, RCAHMW, 14th October 2008)

The name Tomen y Mur means mound of the wall. As the site is on a masonry Roman fort the meaning of the name becomes obvious. The mound itself consists primarily of a jumble of stone, which seems to show its makeup as similar to that of nearby Castell Prysor. It therefore seems logical that the 'motte' was once a tower of some description before it became a mound. Only excavation could ever prove the point.
The castle history may have begun in the late 1070s when Robert Rhuddlan was establishing his rule in the district. The site is said to have been visited by King William Rufus (1087-1100) during one of his North Welsh campaings, but this is not certain. Henry I also seems to have used the castle as a stopping point in 1114. This is the fortresses last mention in the middle ages. Perhaps it too had been demolished in 1094 and never rose again. (Remfry 2016)

The motte is built astride the centre of the NW side of the reduced fort, and may well cover and preserve the gate that must have existed at that point. The motte is about 10 m high and is surrounded by a ditch 4 m wide, with a counterscarp bank surmounted by a modern field wall. The top is uneven, with two principal hollows on SE and SW which may represent the sites of original buildings (or possibly robbing). It is slightly oval, measuring approx. 14 m N-S by 19 m E-W. (Scheduling Report)

Site of historic importance to the Welsh and associated with a Welsh legend as the palace of Lleu Llaw Gyffes.
Is the mound a collapsed tower, as suggested by Remfry? If so what date was the tower/building - Roman? C11? If this is a mound built by heaping up rubble from ruined Roman buildings and walls then it is motte (mottes are built of available materials; earth, turf sods, clay, river pebbles etc. - another possibility might be an earthen motte strongly revetted with building rubble). If it a collapsed tower then it would represent, in this fairly remote area, either an exceptional Roman building or an exceptional C11 masonry building.
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Sources of information, references and further reading
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This record last updated 06/07/2016 19:14:33