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Twyn-y-Gaer is a prehistoric hillfort situated in Wales on bedrock of Lower Devonian age. The underlying mudstone, siltstone and sandstone were formed during the Early Devonian period and create the foundation upon which the fort's defences were constructed. The site is protected as an ancient monument by Cadw, the Welsh heritage body, and holds the reference BR035 within their records.
Hillforts of this type typically date to the Iron Age, though some may have earlier origins, and represent substantial communal investments in defensive architecture. Such fortifications were commonly built on elevated positions to command views across surrounding land, providing both strategic advantage and visibility as centres of settlement and authority.
Twyn-y-Gaer's location upon Lower Devonian geology is characteristic of the upland terrain across much of Wales. The stone beneath the site would have provided natural building material for the construction of ramparts and internal structures. The fort's survival as an earthwork monument reflects both the defensive engineering of its builders and the protective conditions afforded by its landscape setting through subsequent centuries.
Twyn-y-Gaer is a scheduled monument protected by Cadw under reference BR035. View the official record →
Twyn-y-Gaer is a prehistoric hillfort situated in Wales on bedrock of Lower Devonian age. It is designated a Scheduled Ancient Monument by Cadw under reference BR035.
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 BR035.
Several scheduled monuments lie within 10 km, including Pont Gihirych (6.3 km), Nant y Gaseg long hut (6.8 km), Maen Llia Stone (7.1 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.