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Castell Olwen is a prehistoric hillfort located in Wales and protected by Cadw under reference CD161. The site sits upon bedrock formed from Llandovery Rocks, an undifferentiated sequence of mudstone, siltstone and sandstone deposited during the Llandovery period. This geology shaped both the fort's defensive potential and the landscape visible from its ramparts today.
The hillfort exemplifies the settlement pattern of Iron Age Wales, when communities chose elevated positions to command surrounding territory and provide natural defensive advantages. The soft sedimentary bedrock, though offering poor stone for substantial fortification walls, would have presented terrain suitable for the construction of earthen ramparts and ditches characteristic of Welsh hillforts of this period.
Like other upland forts across Wales, Castell Olwen represents an enduring choice of location for settlement and control. The site's position within the broader landscape of prehistoric occupation reflects how communities selected defensible ground, and how geological foundations—whilst perhaps limiting available building materials—provided the topographical advantages essential to Iron Age fortified settlements.
Castell Olwen is a scheduled monument protected by Cadw under reference CD161. View the official record →
Castell Olwen is a prehistoric hillfort located in Wales and protected by Cadw under reference CD161.
Castell Olwen dates from the prehistoric period, and is classified as a hillfort. It is one of over 32,000 scheduled monuments protected across the UK.
Castell Olwen 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 CD161.
Several scheduled monuments lie within 10 km, including Lampeter Pillbox (1.5 km), Caer Pencarreg (5.1 km), Llanwnnen Ring Motte (5.1 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Castell Olwen'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.
Castell Olwen stands on Llandovery Rocks (Undifferentiated), bedrock that formed in the Llandovery. The rock here is mudstone, siltstone and sandstone.