A menhir is a upright standing stone, usually tall but can sometimes be found short and engraved. Sometimes placed as a single monolith, or as part of a group of similar stones, no one really understands the purpose of their existence or where they come from. Theories range from human sacrifice by druids to territorial markers. Yet others believe that they were put there by aliens. It could also be possible that some ancient tribes build them as a form of Phallic worship ensuring fertility for their land and their women. Who really knows.
Why is there a high magnetic field near these stones and what is the relationship of Archaeoastronomy and Stonehenge? Why are there menhirs found all around the world. France, Sweden, Britain, New York, Africa, Germany. The comic Asterix and Obelix made fun of throwing menhirs at the Romans but I doubt that's how they really got where they stand today.
The word menhir was adopted from the French by 19th century archaeologists. It is a combination of two words found in the Breton language; men (stone), and hir (long). In Modern Welsh they are described as maen hir, or "long stone." In modern Breton, the word
peulvan is used. (wiki quote)
To me, it looks like a clock from the sky, a giant sundial if you will, but one will never know and it is so much more fun guessing. What do you think?