Twthill, Caernarfon

Has been described as a Questionable Timber Castle (Motte)

There are uncertain remains

NameTwthill, Caernarfon
Alternative Names
Historic CountryCaernarfonshire
Modern AuthorityGwynedd
1974 AuthorityGwynedd

A probable pre-Roman defended ditch is represented by traces of a rock cut ditch on the summit. However, this looks uncertain and it may possibly have been some form of motte and bailey (Source: OS 495 card). (Coflein–M.Edwards, RCAHMW, 19 October 2001)

A probable pre-Roman 'defended post' on Twthill is represented by the traces of a rock-cut ditch near the summit (Smith). A bank of earth 10ft wide and 4ft high runs in a slight curve from NW to SE across the flat top of the ridge that extends NE from Twthill. Its purpose is uncertain but it does not appear to be defensive. Condition - fair (RCAHMW). The summit of Twthill has a fairly flat and level rock surface which measures 40m E-W by 25m N-S. It bears no traces of occupation but it is ideally suited for since steep rock faces fall sharply on all sides of plateau. There is no indication that the ditch has been artificially cut. The bank is not defensive in itself. Allowing for the curve of the ridge it seems that the bank forms an arc based on the summit of Twthill, and it seems designed to serve some purpose closely associated with the hill. It is unlikely to have been a crude form of hill fort (OS Record). (Gwynedd Archaeological Trust HER)

Gatehouse Comments

A naturally defensive site that could have been used in any period as a retreat and look out but there is no evidence to actual support it being so used. For medieval knights, dependent upon horses, the lack of water would make this an unfavourable site and the least likely occupation of the site is as a medieval 'motte and bailey'.

- Philip Davis

Not scheduled

Not Listed

The National Monument Record (Coflein) number(s)
County Historic Environment Record
OS Map Grid ReferenceSH482630
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Copyright Dave Barlow of Abaroths World All Rights Reserved
Copyright Dave Barlow of Abaroths World All Rights Reserved
Copyright Dave Barlow of Abaroths World All Rights Reserved
Copyright Dave Barlow of Abaroths World All Rights Reserved

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  • Morgan, Gerald, 2008, Castles in Wales: A Handbook (Talybont: Y Lolfa Cyf.) p. 252 (listed as possible)
  • RCAHMW, 1960, A Survey and Inventory of the Ancient Monuments of Caernarvonshire Vol. 2: Central (HMSO) p. 158 no. 1125 online copy


  • Smith, G., 1998, Hut Circle Settlement Survey