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Castell Nos is a medieval motte located in Wales and protected as a scheduled ancient monument by Cadw under reference GM408. The earthwork sits on bedrock of the South Wales Upper Coal Measures Formation, a sequence of mudstone, siltstone, sandstone, coal, ironstone and ferricrete deposited during the Westphalian period of the Carboniferous. This substantial geological foundation provided the medieval builders with a naturally elevated base upon which to construct their defensive work.
The motte represents a common form of Norman and post-Conquest fortification found across Wales and the English border region. Such earthwork castles typically comprised a raised mound crowned by timber or stone structures, surrounded by defensive ditches and palisades. The site's location within the coal-bearing geology of South Wales places it in a landscape shaped by ancient swamp forests and tidal flats, long since transformed into the industrial heartland of Wales.
Today, Castell Nos survives as an earthwork monument bearing witness to medieval patterns of settlement and control. Its preservation under Cadw's guardianship ensures that this record of medieval Welsh fortification remains protected for future study and public understanding of Wales' architectural heritage.
Castell Nos is a scheduled monument protected by Cadw under reference GM408. View the official record →
Castell Nos is a medieval motte located in Wales and protected as a scheduled ancient monument by Cadw under reference GM408.
Castell Nos dates from the medieval period, and is classified as a motte. It is one of over 32,000 scheduled monuments protected across the UK.
Castell Nos 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 GM408.
Several scheduled monuments lie within 10 km, including Tarren Maerdy cairn (E) (3.5 km), Mynydd Maendy Hillfort (4.7 km), Mynydd Ty'n-tyle cairns (4.8 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Castell Nos'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.
Castell Nos 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.