The National Monument Record makes Carnan a’Ghrodhair seem rather more sexy than it is on the ground:
A souterrain was found during the last war during the construction of a Home Guard gun emplacement or look-out post.
When digging the foundations the workmen struck a flagged floor with a large stone in the middle which, when removed, revealed a passage-way leading down at an angle a distance of some 20 to 30ft before opening out into a beehive cell about 6 or 7ft high... About 35ft east of the emplacement there was a slight de- pression with possibly a few stones in it, which seemed to mark the site of the cell.
Mind you, it does warn you that, “the entrance to this souterrain, within the look-out post, is almost fully blocked with rubbish, making access to the chamber impossible”. Apparently the passage was still discernable in 1969.