Castell Crwn

Has been described as a Possible Timber Castle (Ringwork)

There are earthwork remains

NameCastell Crwn
Alternative NamesLlanrhwdrys; Castell Rhonyn
Historic CountryAnglesey
Modern AuthorityAnglesey
1974 AuthorityGwynedd

An oval earthwork enclosure set on low lying ground. Possibly a medieval castle, although it could be a prehistoric settlement enclosure. The enclosure is about 27m north-south by 22m. It is enclosed by a rampart and ditch with a counterscarp remaining on the north-west. There is an east-facing entrance gap. The 4.0-5.0m wide ditch may originally have been a water filled moat. (Coflein–John Wiles 13.08.07)

The monument comprises the remains of a circular earthwork comprising a bank, external ditch and remains of counterscarp bank, with an internal diameter of 24 -25 m. It is situated in a slight depression 20 m E of a small stream flowing N to the sea. The defences are best preserved on the W side, where there is an outer bank 0.3-0.5 m high, a fall to the bottom of the ditch of about 1 m and then a climb of 2 m to the top of the internal bank. The internal bank lies between 0.75 and 1.5 m above the level of the interior. The ditch has been filled in on the E and NE sides, but is still just visible. It is possible that the ditch was filled with water from the adjacent stream. A modern field bank cuts through the S part of the site, causing some damage to the banks. The site is generally better preserved S of this wall, although parts of it are very overgrown with thorn and bramble. A 2 m gap in the interior bank on the E side may represent the original entrance. A shallow gully, possibly a modern drain, runs from the N side of the site. The remains of a bank can be seen in the undergrowth S of the field wall and 10 m W of the outer bank. Its purpose or extent could not be determined. (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 ReferenceSH331908
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  • Morgan, Gerald, 2008, Castles in Wales: A Handbook (Talybont: Y Lolfa Cyf.) p. 251 (listed as possible)
  • Salter, Mike, 1997, The Castles of North Wales (Malvern) p. 49 (slight)
  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 3
  • RCAHMW, 1937, An inventory of the ancient monuments in Anglesey (HMSO) p. 108-9 no. 2 online copy


  • 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 (possible)