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Cwmbiga long cairn is a prehistoric monument located in Wales, built upon bedrock of Llandovery rocks comprising mudstone, siltstone and sandstone. The site is protected by Cadw, the Welsh heritage organisation, under reference MG323.
Long cairns represent one of the earliest forms of monumental architecture in Britain, typically constructed during the Neolithic period as communal burial structures. Built from accumulated stone cleared from the surrounding landscape, these monuments often contain internal chambers and passages aligned to cardinal points or celestial events. Their elongated form, typically between 20 and 100 metres in length, distinguishes them from the later round barrows of the Bronze Age.
The particular geology underlying Cwmbiga—the soft sedimentary rocks of the Llandovery formation—would have influenced how the monument's builders gathered and arranged their materials. The local landscape, shaped by these ancient mudstones and siltstones, provided the stone from which the cairn was constructed, anchoring it physically and culturally to its Welsh setting.
Cwmbiga long cairn is a scheduled monument protected by Cadw under reference MG323. View the official record →
Cwmbiga long cairn is a prehistoric monument located in Wales, built upon bedrock of Llandovery rocks comprising mudstone, siltstone and sandstone. It is designated a Scheduled Ancient Monument by Cadw under reference MG323.
Cwmbiga long cairn dates from the prehistoric period, and is classified as a long cairn. It is one of over 32,000 scheduled monuments protected across the UK.
Cwmbiga long 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 MG323.
Several scheduled monuments lie within 10 km, including Carn Biga, Pumlumon Fawr/Plynlimon (3.4 km), Carreg Wen Prehistoric Standing Stone (3.5 km), Carn Fach Bugeilyn (4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Cwmbiga long 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.
Cwmbiga long cairn stands on Llandovery Rocks (Undifferentiated), bedrock that formed in the Llandovery. The rock here is mudstone, siltstone and sandstone.