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Castell Odo is a prehistoric hillfort situated in Wales on bedrock of Upper Cambrian metasedimentary rock, including Tremadoc formation. The site exploits the natural defensive properties of its hilltop location, a common strategy for Iron Age communities across Britain and Ireland. The Tremadocian geology underlying the fortification provides the stone-rich foundation typical of Welsh hillfort construction. The monument is protected by Cadw, the historic environment service of Wales, under reference CN045, recognising its significance as a scheduled ancient monument.
Hillforts of this type emerged during the Iron Age, roughly 800 BC onwards, serving as defended settlements, administrative centres and refuges for surrounding communities. Castell Odo's positioning reflects the builders' understanding of landscape tactics and resource management. The surrounding terrain would have provided pastoral land and water sources essential for sustaining a defended population.
The monument survives today as an earthwork testimony to Iron Age settlement patterns in Wales. Like many hillforts, it preserves evidence of prehistoric land use and social organisation. The site's survival, protected under the Cadw schedule, allows continued study of Welsh Iron Age fortification practices and the communities who inhabited these significant centres.
Castell Odo is a scheduled monument protected by Cadw under reference CN045. View the official record →
Castell Odo is a prehistoric hillfort situated in Wales on bedrock of Upper Cambrian metasedimentary rock, including Tremadoc formation. It is designated a Scheduled Ancient Monument by Cadw under reference CN045.
Castell Odo 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 Odo 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 CN045.
Several scheduled monuments lie within 10 km, including The Veracius Stone (formerly in Tudweiliog, Dwyfor) (2.5 km), The Senacus Stone (formerly in Tudweiliog, Dwyfor) (2.5 km), Capel Anelog (3.3 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Castell Odo'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 Odo stands on Upper Cambrian, Including Tremadoc, bedrock that formed in the Tremadocian. The rock here is metasedimentary rock.