Victorian Books, A History of the County of Brecknockshire

This Cromlech [Gwernvale Long Barrow [Map]], one end of which adjoined the Brecon turnpike road on the south side, was immediately opposite Gwernvale, about half a mile from Crickhowel: it consisted as usual of a huge tablet of unhewn stone mounted upon five supporters pitched edgewise in the ground, the superincumbent stone or cover, inclining to the south and open in the front to the north: it was placed on a high mound, long overrun with brush wood and brambles, and formerly there seem to have been stones placed edgewise, also round what is now almost a semicircle; whether before the turnpike road was made, they extended so as to describe an irregular circle, I know not, but I am inclined to think that the appearance of the spot was materially altered by the intersection of the highway, and that upon that occasion the workmen, either from curiosity or accident, anticipated our attempt to make discoveries under the Cromlech; in that case the object, though far different from ours, was probably equally unsuccessful .