Dinerth Castle, Castell Allt Craig Arth

Also known as, or recorded in historical documents as; Hero; Monachty; Dinierth; Dineirth

In the community of Dyffryn Arth.
In the historic county of Cardiganshire (Modern authority of Ceredigion, preserved county of Dyfed).

Motte and bailey on a promontory between the Arth and its tributary, the Nant Erthig. There could well have been a prehistoric defence structure here that was adapted in medieval times. There is a strong ditch and linear ridge defence on the eastern side, whilst all other sides fall into steep ravines. There seem to be three separate mounds within the site which covers about 3 ha. Dinerth was originally built by the de Clare family around 1110. It has had an extremely chequered history - razed by Gruffydd ap Rees in 1116, and again by Owain of Gwynedd in 1136. It was occupied by Hywel in 1143, and by Cadwaladr in the following year. In 1158 it became part of the lands ceded by the Normans to Earl Roger of Hereford. It was destroyed yet again by Lord Rhys in 1164, and came into the possession of Maelgwyn who lost it to his brother, but recovered it in 1199. It is thought to have been completely destroyed by Maelgwyn in 1202.

This site has been described as a;
Timber Castle.
The confidence that this site is a medieval fortification or palace is Certain.
Earthworks remains.

This site is a scheduled monument protected by law.

The Ordnance Survey Map Grid Reference is SN495624

Modern Map from Good for landscape form and features	Modern Map from Good for general location
Air Photo from	1st edition OS Map from

Sources of information, references and further reading

National Monuments Record number; 303844

County Sites and Monuments Record number; 1869

• Web site links
  • http://www.castlewales.com/dinerth.html
    http://www.castlewales.com/gilbert.html
• Books
  • Pettifer, Adrian, 2000, Welsh Castles, A Guide by Counties (Boydell Press) p41
    Davis, Paul, 2000, A Company of Forts. A Guide to the Medieval Castles of West Wales (Gomer Press) p31-2 [reconstruction]
    Salter, Mike, 1996, The Castles of South West Wales (Malvern) p26 [plan]
    King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol1 p45
    Fry, P.S., 1980, Castles of the British Isles (David and Charles) p348-9
    Renn, D.F., 1973 (2edn), Norman Castles of Britain (John Baker)
    Owen, Henry (ed), 1936, The Description of Pembrokeshire (London) Vol4 p492-3
    Armitage, Ella, 1912, The Early Norman Castles of the British Isles (London: John Murray) p282-3
• Journal Articles
  • Hogg, A.H.A. and King, D.J.C., 1963, 'Early castles in Wales and the Marches: a preliminary list' Archaeologia Cambrensis Vol112 p77-124
    Brown, R, Allen, 1959, 'A List of Castles, 1154–1216' English Historical Review Vol74 [Reprinted in Brown, R. Allen, 1989, Castles, conquest and charters: collected papers (Woodbridge: Boydell Press)] pp90-121
    King, 1956, Ceredigion Vol3 p57-8