Castell Trefadog

Has been described as a Possible Timber Castle (Other/Unknown)

There are earthwork remains

NameCastell Trefadog
Alternative NamesPorth Trefadog
Historic CountryAnglesey
Modern AuthorityAnglesey
1974 AuthorityGwynedd

Very heavily-defended coastal site. Recent excavation revealed the foundations of C14 stone house inside an enclosure. An unusual site, perhaps akin to Penmaen Castle, Gower. Some have suggested a Viking origin for the site, others call it native welsh. Undergoing coastal erosion. In CARN listed as early medieval promontory fort, prehistoric coastal promontory fort and unknown fort.

A natural coastal knoll has been enhanced with a rampart and ditch to form a promontory fort. The knoll has been eroded by the sea on the north-west and north-east and only a near square area about 18m across remains of what may have been a rather larger enclosure. The 1.8m deep ditch on the south-east side takes advantage of a natural gully and on this side the rampart rises 3.4m from the ditch bottom. Slighter banks on the noth-east and north-west sides are probably old field boundaries. No finds are known from the site and its original date is unknown. It is perhaps most likely to be a later Prehistoric or Roman period fort. The traditional identification as a medieval earthwork castle ('Castell - site of': on OS County series 1st edition (Anglesey V.12 1889)) is perhaps unlikely. (Coflein–John Wiles 13.08.07)

A defended site with the sea on the N and W sides, a natural gully to the SE and a massive bank and ditch to the SW. The site has recently been excavated, and was shown to have comprised a level promontory defended by a bank, now surviving to a height of 2 m, inside a ditch 13 m wide and 4 m deep. The interior occupies some 250 sq. m, but some on the NW side has been lost through erosion of the cliff face. A large rectangular structure with rounded corners occupies the NW part of the interior. (Scheduling Report)

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 ReferenceSH290859
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Copyright Dave Barlow of Abaroths World All Rights ReservedView full Sized Image
Copyright Dave Barlow of Abaroths World All Rights ReservedView full Sized Image

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  • Morgan, Gerald, 2008, Castles in Wales: A Handbook (Talybont: Y Lolfa Cyf.) p. 231 (listed)
  • Pettifer, Adrian, 2000, Welsh Castles, A Guide by Counties (Boydell Press) p. 7
  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 2
  • RCAHMW, 1937, An inventory of the ancient monuments in Anglesey (HMSO) p. 68-9 no. 3 online copy


  • King, D.J.C. and Alcock, L., 1969, 'Ringworks in England and Wales' Château Gaillard Vol. 3 p. 90-127 p. 90-127
  • 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