Castell Prysor

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

There are earthwork remains

NameCastell Prysor
Alternative NamesCwm Prysor
Historic CountryMerioneth
Modern AuthorityGwynedd
1974 AuthorityGwynedd

The medieval castle mound known as Castell Prysor is formed from an outcrop upon a spur projecting from the hillside above the Prysor valley. There are ruins of several buildings and terraces and enclosures, to the west and east. This is thought to have been a princely court, or llys. A later building (NPRN 28274) occupies an earlier building platform. This is one of several instances in Merioneth where an apparently unfortified mansion or court is associated with a castle mound, for example Crogen (NPRN 306558) and Rug (NPRN 306598). At Aber in Caernarvonshire a thirteenth century court (NPRN 309171) was excavated at the foot of a castle mount (NPRN 95692). A natural rock boss has been formed into a high steep sided mound by the addition of a mass of stones set in clay, retained by a massive spiralling wall. The resulting mound is in the region of 40-50m across and 15-25m high, with a level summit 8.0-13m across. Pennant noted traces of a round tower in the late eighteenth century (Tours ii, 111-12). The castle mound has no certain outworks. Pennant's notice of 'many Roman coins & urns' being found here may be no more than a figure of speach. (Coflein–John Wiles, RCAHMW, 09.07.07)

This natural boss of rock is strengthened and topped by a stone mound which was originally revetted with dry walling, now badly ruined. Edward I wrote a letter from here on 1 July 1284, but it is obviously an earlier Welsh castle. (Lynch, 1995)

A motte and bailey with the foundations of rectangular structures and enclosures NE and W of the motte. The top of the motte stands some 9 m above the level of the bailey, and is 12 m in diameter. The top has been severely damaged by trenches dug across; the principal trench is 6 m across and nearly 2 m deep. The body of the motte is mainly of stone, and revetted stonework is still visible on the sides of the motte, although blackthorn obscures much of this work

The bailey also makes use of natural outcrops of rock, and is defended on the W by a bank 3 m wide and 0.6 m high. There is a small, rock-cut pool in the SW corner of the bailey. (Scheduling Report)

The site of Prysor castle lies high in a steep valley controlling the route from Bala to Tremadog. It has no known history before King Edward I stayed there while surveying his new lands in Wales after the fall of Prince Llywelyn ap Gruffydd (d.1282). That the castle does not appear again in the written record would suggest that the king found his sojourn here uncomfortable and the upkeep of this isolated fortress was considered no longer necessary. We have no idea who built the castle, other than the suggestion that it was a predecessor of Prince Llywelyn.

The ruins consist of a large pile of stones, often wrongly described as a motte. An old print shows that this was once a stone tower which has now collapsed in on itself. Towards the rising hillside was a weak bailey, in which there are the remains of buried portions of what appears to be a hall block, unless it was a later farm. (Remfry 2016 >]

Gatehouse Comments

This may well have been a clay bonded round masonry tower, probably of C13 date. The existence of an earlier castle, or high status site, here is absent but, by analogue, it is not reasonable to think there was some earlier occupation although the form of residence is unknown.

- 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 ReferenceSH757368
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  • Davis, Paul, R., 2011, The Forgotten Castles of Wales (Almeley: Logaston Press) p. 43-4
  • Kenyon, John, 2010, The Medieval Castles of Wales (University of Wales Press) p. 19
  • Butler, L., 2009, 'The Castles of the Princes of Gwynedd' in Willams, D. and Kenyon, J. (eds), The Impact of the Edwardian Castles in Wales (Oxbow) p. 27-36
  • Morgan, Gerald, 2008, Castles in Wales: A Handbook (Talybont: Y Lolfa Cyf.) p. 241 (listed)
  • Davis, Paul R., 2007, Castles of the Welsh Princes (Y Lolfa) p. 44-5
  • 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. 408-9
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  • Reid, Alan, 1998, Castles of Wales (John Jones Publishing) p. 55
  • Salter, Mike, 1997, The Castles of North Wales (Malvern) p. 27
  • Lynch, Frances, 1995, A Guide to Ancient and Historical Wales: Gwynedd (London: HMSO)
  • Davis, Paul R., 1988, Castles of the Welsh Princes (Swansea)
  • Avent, Richard, 1983, Castles of the Princes of Gwynedd (Cardiff)
  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus)
  • Fry, P.S., 1980, Castles of the British Isles (David and Charles) p. 374
  • RCAHMW, 1921, An inventory of the Ancient Monuments of Merionethshire (HMSO) p. 179 no. 568 online copy
  • Lewis, Samual, 1849, A Topographical Dictionary of Wales online copy
  • King, Edward, 1804, Munimenta antiqua or Observations on antient castles (W.Bulmer and Co) Vol. 3 p. 124 online copy


  • de Levandowicz, Martin, 1998, ' A Survey of Castell Prysor, Meirionnydd' Archaeology in Wales Vol. 38
  • Avent, Richard, 1994, 'Castles of the Welsh Princes' Château Gaillard Vol. 16 p. 11-17
  • 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
  • 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
  • Gresham, C.A. and Hemp, W.J., 1949, ‘Castell Prysor’ 96th Annual Meeting: Programme, 1949, CAA p. 23 (reprinted in the 1971 Harlech Programme p. 26-7)
  • Gresham, C.A. and Hemp, W.J., 1948-9, Archaeologia Cambrensis Vol. 100 p. 312-3

Primary Sources

  • Edwards, J.G. (ed), 1940, Littere Wallie, preserved in Liber A (Cardiff) p. 170