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Gwern-y-Domen Castle Mound is a medieval motte constructed on bedrock of the South Wales Upper Coal Measures Formation. The underlying geology of mudstone, siltstone and sandstone, interspersed with coal and ironstone seams, shaped the landscape in which this fortification was built. The ferricrete deposits typical of this geological formation would have weathered into a reddish soil across the surrounding terrain.
The motte itself represents a common form of Norman and post-Conquest military architecture in Wales, consisting of an artificially raised earthen mound designed to elevate a timber or stone fortification above the surrounding ground. Such structures typically commanded local territory and served defensive and administrative purposes for medieval lordships. The choice of this particular site reflects the strategic importance of the location within its region.
The monument is now protected by Cadw under reference GM218, recognising its significance as evidence of medieval settlement and military organisation in Wales. The motte survives as an earthwork, its form preserved in the landscape to record more than nine centuries of Welsh history.
Gwern-y-Domen Castle Mound is a scheduled monument protected by Cadw under reference GM218. View the official record →
Gwern-y-Domen Castle Mound is a medieval motte constructed on bedrock of the South Wales Upper Coal Measures Formation. It is designated a Scheduled Ancient Monument by Cadw under reference GM218.
Gwern-y-Domen Castle Mound dates from the medieval period, and is classified as a motte. It is one of over 32,000 scheduled monuments protected across the UK.
Gwern-y-Domen Castle Mound is a Scheduled Ancient Monument, legally protected by Cadw — the body responsible for designating and safeguarding heritage sites in Wales. The official designation reference is GM218.
Several scheduled monuments lie within 10 km, including Wenallt Camp, Rhiwbina (5.6 km), Twmpath, Rhiwbina (6.1 km), Castell Coch (6.8 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Gwern-y-Domen Castle Mound's history, each drawn from the record and mapped to the exact spot:
Every location is different. Not every section appears for every place, only what the historical record actually holds turns up in a report.
Gwern-y-Domen Castle Mound stands on South Wales Upper Coal Measures Formation, bedrock that formed in the Westphalian. The rock here is mudstone, siltstone, sandstone, coal, ironstone and ferricrete.