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Castell Collen is a Roman fort situated in Wales, strategically positioned on bedrock composed of Llandovery rocks—undifferentiated mudstone, siltstone and sandstone formations dating to the Llandovery period. The site's geology reflects the ancient sedimentary landscape of mid-Wales, providing a stable foundation for military construction during the Roman occupation of Britain.
The fort represents a significant example of Roman military architecture in the Welsh interior, where such installations served to control territory and maintain supply routes through challenging terrain. The underlying Llandovery rocks, whilst providing adequate building material, presented particular engineering considerations for the fort's foundations and defensive ditches.
Castell Collen is now protected by Cadw under reference RD001, recognising its importance as a scheduled ancient monument. The site remains a valuable archaeological resource for understanding Roman military strategy and occupation patterns in Wales, with its position and construction reflecting Rome's approach to frontier consolidation in the western reaches of the province of Britannia.
Castell Collen is a scheduled monument protected by Cadw under reference RD001. View the official record →
Castell Collen is a Roman fort situated in Wales, strategically positioned on bedrock composed of Llandovery rocks—undifferentiated mudstone, siltstone and sandstone formations dating to the Llandovery period. It is designated a Scheduled Ancient Monument by Cadw under reference RD001.
Castell Collen dates from the roman period, and is classified as a fort. It is one of over 32,000 scheduled monuments protected across the UK.
Castell Collen 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 RD001.
Several scheduled monuments lie within 10 km, including Cwm-berwyn round cairn (8.9 km), Carneddau Round Cairn (8.9 km), Bryntwppa stone row (9.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Castell Collen'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 Collen stands on Llandovery Rocks (Undifferentiated), bedrock that formed in the Llandovery. The rock here is mudstone, siltstone and sandstone.