Blaen Duhonw warren lies 4265m east-south-east of Llangammarch Wells, on a NW facing hill above the valley of Blaen Duhonw. Four rectangular pillow mounds, the largest 13.8m x 6.6m. There is a 5th mound 138m west-north-west on the hill across the river. Related to The Warren (NPRN 90329) located to the north. Possibly related to settlement (NPRN 90333), 71m to the north.