Hidden away among the homes of Locmariaquer village you'll see the sign to Mané er Hroeuk tumulus. There's a parking place right by it. This is a right big bugger of a mound and from what I could see rather untidy on the outside; there is no clear profile.
Steps have been constructed that lead down into the tomb. A short low passageway takes the visitor into a single large roughly round chamber. The chamber is lined with big slabs, but with no carvings that I could see. Above the wall slabs is a rough attempt at corbelling before the whole thing is topped with two giant capstones.
We first visited the Manne-er-Hroek, the Montagne de la Fee, or de la
Femme, which bears in the marine charts the name of "Butte de Cesar," for it was the fashion with antiquaries to attribute to Caesar and the Romans every Celtic monument, although bearing no resemblance whatever to any
work of these conquerors.
The guide who furnished the light and showed us the grotto is the widow of a Polish officer. She had a Scotch terrier, which she wanted us to accept. The legend of the mound is this:--A widow had the misfortune of losing her only solace, her son, compelled by law to embark for foreign lands. Years rolled by; he did not return. All said he was lost; but the heart of a mother hopes for ever, and the sad Armorican went every day to the point of Kerpenhir, whence she
surveyed the ocean, and searched the depths of the horizon with tearful eyes for the purple sail which was to bring joy and peace to her dwelling.
One day, when she was returning sad as usual to her desolate home, she was accosted by an old woman, who enquired the cause of her
troubles; and, on hearing them, advised her to heap a pile of stones, so that, mounting on the summit, she might see to a greater distance, and perhaps discern the long looked-for vessel. During the whole night the two women worked, and carried in their aprons the stones they gathered on the heath. In the morning their task was finished, and the Bretonne was scared to see the enormous heap that had been piled together; but the other quieted her fears, and helped her to climb to the top, whence soon the happy mother beheld the vessel of her son. The fairy, her assistant, had disappeared.
This story evidently bears a vague tradition of this tumulus having been raised by a woman, and of some maritime expedition made by him for whom it was probably destined. The name of fairy is attached in Brittany to everything--mountains, springs, grottoes, rocks; every accident in nature is explained by a fairy origin.
From 'Brittany & Its Byways' by Fanny Bury Palliser (1869), which you can read on Project Gutenberg.