© Mapbox · © OpenStreetMap contributors · Boundary data © Cadw
Bwrdd y Tri Arglwydd Boundary Stone is a prehistoric marker stone located in Wales, protected by Cadw under reference ME025. The monument stands upon bedrock of Ludlow age, a geological formation composed of mudstone, siltstone and sandstone that dates to the Silurian period. This stable foundation of mixed sedimentary rock would have provided an ideal base for a substantial stone marker in ancient times.
The stone served as a territorial boundary marker in prehistory, a common practice across upland and frontier regions of Britain. Such monuments typically marked divisions between communities or land holdings, and their placement on prominent or natural meeting points made them effective territorial references. The stone's survival to the present day reflects both its size and the enduring importance of the boundary it marked.
The monument remains a significant record of prehistoric land organisation and settlement patterns in Wales. Its preservation under Cadw protection ensures that this ancient marker continues to document the territorial arrangements of communities who worked and lived upon these Silurian bedrock landscapes thousands of years ago.
Bwrdd y Tri Arglwydd Boundary Stone is a scheduled monument protected by Cadw under reference ME025. View the official record →
Bwrdd y Tri Arglwydd Boundary Stone is a prehistoric marker stone located in Wales, protected by Cadw under reference ME025.
Bwrdd y Tri Arglwydd Boundary Stone dates from the prehistoric period, and is classified as a boundary stone. It is one of over 32,000 scheduled monuments protected across the UK.
Bwrdd y Tri Arglwydd Boundary Stone 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 ME025.
Several scheduled monuments lie within 10 km, including Two Cairns North of Plasnewydd (6.2 km), Deeside Slateworks (6.5 km), Pont Dyfrdwy (7.6 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Bwrdd y Tri Arglwydd Boundary Stone'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.
Bwrdd y Tri Arglwydd Boundary Stone stands on Ludlow Rocks (Undifferentiated), bedrock that formed in the Ludlow. The rock here is mudstone, siltstone and sandstone.