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Caer Idris Hillfort is a prehistoric hillfort situated in Wales and protected as an ancient monument by Cadw. The site occupies ground underlain by Dinantian rocks of Mississippian age, a geological formation dominated by limestone with interspersed sandstone and argillaceous strata. This solid limestone bedrock would have offered both practical advantages for construction and natural defensive strength to the hillfort's position.
The monument is typical of Iron Age fortified settlements found across Wales, where elevated terrain was selected to command views across the surrounding landscape. The underlying Dinantian limestone, whilst harder to work than softer rocks, would have provided stable foundations for the ramparts and other structures that characterised such defended settlements. The mixed geology of the bedrock—combining resistant limestone with more friable sandstone and clay-rich rocks—reflects the complex stratigraphy common to South Wales during this geological period.
As a scheduled ancient monument under Cadw's protection, Caer Idris Hillfort remains an important archaeological site within Wales's prehistoric heritage. The specific characteristics of the site, shaped by both its elevated position and underlying geology, contribute to understanding how Iron Age communities selected and utilised naturally defensible locations across the Welsh landscape.
Caer Idris Hillfort is a scheduled monument protected by Cadw under reference AN051. View the official record →
Caer Idris Hillfort is a prehistoric hillfort situated in Wales and protected as an ancient monument by Cadw. It is designated a Scheduled Ancient Monument by Cadw under reference AN051.
Caer Idris Hillfort dates from the prehistoric period, and is classified as a hillfort. It is one of over 32,000 scheduled monuments protected across the UK.
Caer Idris Hillfort 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 AN051.
Several scheduled monuments lie within 10 km, including Segontium Roman Fort (5.7 km), Carreg Lefain Cairn (7.8 km), Parc y Gleision Standing Stone (8.1 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Caer Idris Hillfort'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.
Caer Idris Hillfort stands on Dinantian Rocks (Undifferentiated), bedrock that formed in the Mississippian. The rock here is limestone with subordinate sandstone and argillaceous rocks.