A suggestive legend, full of mythological references, is recounted by the local villagers. 
The story starts with the commencement of the work to build the church of Santa María (St Mary) in Eunate.  For some unknown reason the master stone mason, a member of the community of monks and responsible for carving the church doorway, had to go away.  Work on the building continued without him until finally, when it was almost completed and given the stone mason’s continued absence, the monks were obliged to seek the aid of a huge, old stone mason living in the valley and whose father and grandfather had also been stone masons.
This huge man, who unquestionably had supernatural powers, completed the commissioned task in an incredibly short space of time and produced a perfect work of art. The master stone mason returned shortly afterwards and, seeing the completed creation, he indignantly went to see the abbot and complain that someone had usurped his work.
The abbot, a stern Templar warrior, decided to punish the conceited mason and ordered him to carve another doorway, comparable to the one carved by the old stone mason, and in the same time that it had taken him to do so: three days.
In desperation, given the impossibility of the undertaking, and even prepared to call on the Devil himself to come to his aid, the monk wandered aimlessly through the woods. There he came across the witch, Lamiñak who lived at the source of the river Nekeas.  She took pity on him and told him the magic secret that would solve his difficult problem.
Following her advice, the monk hid himself away by the river Robo, lying in wait for the great snake which ritually came to bathe in the river every year on the night of St John.  Before plunging into the water, the reptile very carefully placed on the river bank the object it had been carrying in its mouth:  the moonstone.  The builder grabbed the stone and made his escape: he had to fill the golden chalice with water from the river Nekeas, drop in the stone and reach the Eunate door as quickly as possible,  having already constructed a rough, un-worked portico opposite the door.
The monk waited for the moonlight to shine on the chalice and, at that very moment, he discovered the synergic power of the stone, the water and the chalice. And, shining over this combination, the light of the moon, on the night of its full force, presiding over the magical spell performed by the master stone mason. In an instant, the figures on the stone carving on the doorway of Santa Maria were reproduced on the rough stonework opposite.
Except that, in the excitement of the moment, his hand had shaken, causing a slight difference.  The spell on this combination of elements (moon – sky; stone – earth; chalice – blood – fire, and water) had indeed achieved the miracle of reproducing the stone carving on the doorway, but as a mirror image.
On the following morning, with the monastic community still dazed by this extraordinary wonder, the huge, old stone mason made his regular visit to enjoy the beauty of his creation only to discover the new doorway in front of his own. In a rage, he gave it such a kick that he sent it flying to the nearby village of Olcoz,  where it still remains today.
Excerpt from the book “Curiosidades del Camino de Santiago” (Curiosities about the Way of St James).  Author: Juan Ramón Corpas Mauleon.  Published by Edilesa