Blog – Y Werthyr Hillfort.

  • Anglesey.
  • Wales
  • OSGB – SH 375000 78200.
  • Scheduled Monument.


Marsh Fort.

This roughly circular fort is situated above the marshland in the area and this protects three sides of the site. The southern side being the only one which faces dry land. The Afron Caradog water course runs across its northern side.

Looking north over Y Werthyr Hillfort.

Y Werthyr Hillfort is defended by double concentric ramparts, with that increasing to three on the northwestern side. Interestingly enough, there are no ditches – impossible in marsh land? Overall the site covers 3.7 hectares with the internal enclosure measuring 182.8m by 201.7m. On the western side is a retaining wall at one of the ramparts.

Looking northeast over Y Werthyr Hillfort.

As you can see from the images, the site sits high above the surrounding landscape. The views from within the defences would have been far reaching.

A road, the B152, has been cut through the western side of the fort. I have not been able to find out if an archaeological investigation was undertaken when the road was constructed.

The site has been ploughed over intensely so there would be little evidence of any settlement, if there had indeed been some. The only archaeological evidence in the area is a terret ring – horse dressing from the Iron Age.  There has been mention of some rescue archaeology being undertaken but no reports or information is available.

Looking east over Y Werthyr Hillfort.

There is no timeline for this site – shock, horror!! Looking at the aerial image I see there are the cropmarks of some buildings to the east, running southeast. A full archaeological investigation of this site is needed! There is so much we can learn from it, plus there is a possibility that the cropmarks of the buildings could be Roman? Anything is possible – we need to know!!!

Aerial view of Y Werthyr Hillfort.
Note the cropmarks of buildings along the south eastern edge of the hillfort.

I leave you with wise words from S. Norton who has written a great book on Marsh Forts,

“Symbolically it is impossible to separate wetlands from acts of votive deposition, rites of passage and religious practice….Water and bog have long been seen as transitory membranes through which people (and objects) may pass to access a spiritual dimension” (Norton, 2021).


With the situation of this site, lack of archaeological investigation and the mystery of its past, are we looking at a settlement, or something of a more ritual nature?

Looking southeast over Y Werthyr Hillfort.


Further Questions –

  • Why has so little attention been paid to this site in the past?
  • Where are the details and information pertaining to the ‘rescue archaeology’ that was carried out?
  • Are there any plans to investigate this site in the near future?
  • What was the role of this Marsh Fort?
  • Are there any possible connections with the Druids who once held this small island?
  • When was the site constructed and occupied?



References & Bibliography.

Brown. I. 2009. Beacons in the Landscape: The Hillforts of England and Wales. Windgather Press.

Cathrall. W., & Ramsey. Sir. A. C. 1860. A Guide Through North Wales. Edward Stanford.

Coflein. 2023. Site Record – Y Werthyr Hill Fort. Available at

Her Majesty’s Stationary Office. 1960. An Inventory of the Ancient Monuments in Anglesey. Volume 2. HMSO.

Norton. S. 2021. Assessing Iron Age Marsh-Forts: With Reference to the Stratigraphy and Palaeoenvironment Surrounding The Berth, North Shropshire. Archaeopress Publishing Limited.

Oxford Archaeology. 2023. WA1766 y Werthyr, Bryngwran, Isle of Anglesey. Atlas of Hillforts of Britain and Ireland. Available at

RCAHMW. 1976. An Inventory of the Ancient Monuments in Glamorgan: Pre-Norman. Part II The Iron Age and Roman Occupation. Volume 1. RCAHMW.

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