Tomen y Mur, Maentwrog

Has been described as a Certain Timber Castle (Motte), and also as a Certain Palace (Other)

There are earthwork remains

NameTomen y Mur, Maentwrog
Alternative NamesMur Castell; Heririmons
Historic CountryMerioneth
Modern AuthorityGwynedd
1974 AuthorityGwynedd

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)

Gatehouse Comments

Site of historic importance to the Welsh and associated with a Welsh legend as the palace of Lleu Llaw Gyffes.

- Philip Davis

This site is a scheduled monument protected by law

Not Listed

The National Monument Record (Coflein) number(s)
County Historic Environment Record
OS Map Grid ReferenceSH705386
HyperLink HyperLink HyperLink
Copyright Jeff Buck and licensed for reuse under this Creative Commons license.
Copyright Eric Jones and licensed for reuse under this Creative Commons license.
Copyright Jeff Buck and licensed for reuse under this Creative Commons license.
Copyright Darren Haddock and licensed for reuse under this Creative Commons license.

Most of the sites or buildings recorded in this web site are NOT open to the public and permission to visit a site must always be sought from the landowner or tenant.

Calculate Print


  • Kenyon, John, 2010, The Medieval Castles of Wales (University of Wales Press) p. 38
  • Morgan, Gerald, 2008, Castles in Wales: A Handbook (Talybont: Y Lolfa Cyf.) p. 167-8
  • King, D.J.C. with Kenyon, J.R., 2001, 'The Castles: a Study in Military Architecture' in Smith J.B. and Smith L.B. (eds), History of Merioneth Vol. 2 p. 415
  • Pettifer, Adrian, 2000, Welsh Castles, A Guide by Counties (Boydell Press) p. 119-20
  • Salter, Mike, 1997, The Castles of North Wales (Malvern) p. 49 (slight)
  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 277
  • Avent, Richard, 1983, Castles of the Princes of Gwynedd (Cardiff)
  • Fry, P.S., 1980, Castles of the British Isles (David and Charles) p. 381
  • Renn, D.F., 1973 (2 edn.), Norman Castles of Britain (London: John Baker) p. 323-4
  • RCAHMW, 1921, An inventory of the Ancient Monuments of Merionethshire (HMSO) p. 151-3 no. 492 online copy
  • Armitage, Ella, 1912, The Early Norman Castles of the British Isles (London: John Murray) p. 261-2 online copy


  • Kenyon, John R., 1996, 'Fluctuating Frontiers: Normanno-Welsh Castle Warfare c. 1075 to 1240' Château Gaillard Vol. 17 p. 119-126
  • Hogg, A.H.A. and King, D.J.C., 1963, 'Early castles in Wales and the Marches: a preliminary list' Archaeologia Cambrensis Vol. 112 p. 77-124
  • Hemp, W.J., 1949, ‘Tomen-y-Mur. The motte’ 96th Annual Meeting: Programme, 1949, CAA p. 22-3
  • Hemp, W.J., 1949-9, Archaeologia Cambrensis Vol. 100 p. 312
  • Gresham, C.A., 1938, 'The Roman fort at Tomen-Y-Mur' Archaeologia Cambrensis Vol. 93 p. 192-211
  • Grover, J.W., 1871, 'Heririmons, or Castell Tomen-y-Mur' Journal of the British Archaeological Association Vol. 27 p. 277-81 online copy

Primary Sources

  • Jones, Arthur (ed), 1910, History of Gruffydd ap Cynan (Manchester) p. 140-1, 152-3 online copy