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Castell Mawr Mound and Bailey Castle is a medieval motte and bailey earthwork located in Wales and protected by Cadw under reference CM131. The castle occupies a naturally strategic position, with its earthworks constructed upon bedrock of Ashgill formation rocks, a sequence of mudstone, siltstone and sandstone that provided a stable foundation for medieval fortification. This geological base would have offered good drainage and resistance to erosion of the castle's defensive banks and ditches.
The site comprises the characteristic features of motte and bailey design: a raised mound, or motte, that would have supported a wooden tower or palisade, surrounded by an outer courtyard or bailey defended by its own rampart and ditch. This form of castle became widespread throughout Britain and Wales following the Norman conquest, serving as efficient garrison strongholds in newly conquered territories. The compact, straightforward design allowed rapid construction whilst maintaining effective defensive capability.
The underlying Ashgill rocks would have constrained the precise placement and depth of ditches during construction, yet the mound itself demonstrates successful adaptation to local geology. The site's preservation reflects the durability of earthwork fortifications, which remain archaeologically legible centuries after their timber superstructures have disappeared.
Castell Mawr Mound and Bailey Castle is a scheduled monument protected by Cadw under reference CM131. View the official record →
Castell Mawr Mound and Bailey Castle is a medieval motte and bailey earthwork located in Wales and protected by Cadw under reference CM131.
Castell Mawr Mound and Bailey Castle dates from the medieval period, and is classified as a motte and bailey. It is one of over 32,000 scheduled monuments protected across the UK.
Castell Mawr Mound and Bailey Castle 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 CM131.
Several scheduled monuments lie within 10 km, including Castell Bach (0.3 km), Crug Hywel Round Barrow (3.3 km), Pant-Glas Round Barrow (3.3 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Castell Mawr Mound and Bailey Castle'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 Mawr Mound and Bailey Castle stands on Ashgill Rocks (Undifferentiated), bedrock that formed in the Ashgill. The rock here is mudstone, siltstone and sandstone.