Pen y Castell, Garreg Olau

Has been described as a Possible Timber Castle (Other/Unknown), and also as a Possible Masonry Castle

There are masonry footings remains

NamePen y Castell, Garreg Olau
Alternative NamesCaer Oleu; Careg Oleu Rhiw Dafnau Maenan
Historic CountryCaernarfonshire
Modern AuthorityConwy
1974 AuthorityGwynedd
CommunityLlanddoged and Maenan

On a narrow ridge with precipitous sides. Access from the N is prevented by a ditch about 5' deep cut across the ridge. S of this is a D-shaped enclosure with a strong wall dry built in rubble masonry and still standing 3' high in places. There is no entrance. The enclosure contains a small ditch, possibly the foundation trench of a round wooden tower. S of this enclosure the edges of the ridge are reinforced with stone walling, generally poorly preserved except on the NW. The enclosed area is divided into 3 sections by natural crags. The structure may possibly be the result of native adaptation of the "motte and bailey" layout to an unusual site. Much ruined. (Gwynedd Archaeological Trust HER ref. RCAHMW)

Pen y Castell compares in some measure with two Iron Age forts, Caer Seion on Conway Mountain and Garm Bodvan. Both feature a small strong inner bank set at one end, or side, of a large defended area. (Gwynedd Archaeological Trust HER ref. OS record)

Gatehouse Comments

This is not a Norman castle but local welsh lords do seem to have been more likely to reuse Iron Age site which had been built by their direct ancestors and which often maintained some cultural importance. Whether or not this happened here is likely only to be answered by extensive destructive archaeology.

- 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 ReferenceSH793666
HyperLink HyperLink HyperLink

No photos available. If you can provide pictures please contact Castlefacts

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  • Davis, Paul, R., 2011, The Forgotten Castles of Wales (Almeley: Logaston Press) p. 52-54
  • Davis, Paul R., 2007, Castles of the Welsh Princes (Y Lolfa) p. 65
  • Pettifer, Adrian, 2000, Welsh Castles, A Guide by Counties (Boydell Press) p. 36
  • Avent, Richard, 1983, Castles of the Princes of Gwynedd (Cardiff)
  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 35
  • RCAHMW, 1956, A Survey and Inventory of the Ancient Monuments of Caernarvonshire Vol. 1: East (HMSO) p. 168 no. 609 online copy


  • Hogg, A.H.A. and King, D.J.C., 1967, 'Masonry castles in Wales and the Marches: a list' Archaeologia Cambrensis Vol. 116 p. 71-132 (possible)
  • 1882, Archaeologia Cambrensis Vol. 37 p. 333 online copy