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Pen Allt-mawr platform cairn is a prehistoric platform cairn located in Wales and protected by Cadw under reference BR305. Platform cairns are ritual or domestic structures built during the Neolithic period, consisting of a deliberately levelled platform constructed from stone and rubble, often fronted by a kerb. The form represents a significant development in prehistoric monument building, distinct from earlier burial cairns and later ceremonial structures.
The cairn sits upon Lower Devonian bedrock of sandstone and conglomerate, rocks formed during the Early Devonian period and now interbedded through ancient geological processes. This solid foundation of local stone would have provided both practical building material and a stable base for construction. The geology directly shaped the monument's form, as communities working this landscape would have drawn upon the naturally fractured stone available at the site.
Pen Allt-mawr's survival and protection reflect the importance of platform cairns to understanding prehistoric settlement patterns and ritual practice in Wales. The specific location on this bedrock formation, in combination with other archaeological evidence from the surrounding area, contributes to knowledge of how Neolithic communities adapted their monumental practices to particular landscapes and local geological conditions.
Pen Allt-mawr platform cairn is a scheduled monument protected by Cadw under reference BR305. View the official record →
Pen Allt-mawr platform cairn is a prehistoric platform cairn located in Wales and protected by Cadw under reference BR305.
Pen Allt-mawr platform cairn dates from the prehistoric period, and is classified as a platform cairn. It is one of over 32,000 scheduled monuments protected across the UK.
Pen Allt-mawr platform cairn 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 BR305.
Several scheduled monuments lie within 10 km, including Hen Castell (7.8 km), Cwrt-y-Gollen Standing Stone (7.9 km), Coed Pentwyn Hillfort (8.2 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Pen Allt-mawr platform cairn'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.
Pen Allt-mawr platform cairn stands on Lower Devonian Rocks (Undifferentiated), bedrock that formed in the Early Devonian. The rock here is sandstone and conglomerate, interbedded.