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Twyn-y-Gaer is a prehistoric hillfort located in Wales and protected by Cadw as a scheduled ancient monument. The fort sits upon bedrock of Lower Devonian age, comprising mudstone, siltstone and sandstone formed during the Early Devonian period. These metamorphic rocks would have provided the raw materials for the fort's construction, with stone readily available for rampart building and defensive structures characteristic of Iron Age hillforts in the region.
The site exploits the natural topography of its Devonian bedrock foundation, a common strategy for Welsh hillfort placement. The combination of naturally elevated terrain and locally quarried stone enabled builders to construct substantial fortifications. The exposed geological layers visible on the slopes would have been familiar to prehistoric communities across this landscape.
Twyn-y-Gaer represents an important element of Iron Age settlement and territorial control in Wales. Its survival and official protection reflect the archaeological significance of hillforts as evidence of prehistoric social organisation, defence and land use. The monument contributes to our understanding of Iron Age communities who inhabited the Welsh uplands and exploited the geology beneath them.
Twyn-y-Gaer is a scheduled monument protected by Cadw under reference BR044. View the official record →
Twyn-y-Gaer is a prehistoric hillfort located in Wales and protected by Cadw as a scheduled ancient monument.
Twyn-y-Gaer dates from the prehistoric period, and is classified as a hillfort. It is one of over 32,000 scheduled monuments protected across the UK.
Twyn-y-Gaer 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 BR044.
Several scheduled monuments lie within 10 km, including Roman Road on Mynydd Illtyd, south-western section (5.1 km), Standing Stone near Traeth Bach (5.3 km), Waunfaeog Hillfort (6.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Twyn-y-Gaer'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.
Twyn-y-Gaer stands on Lower Devonian Rocks (Undifferentiated), bedrock that formed in the Early Devonian. The rock here is mudstone, siltstone and sandstone.