Hmmm...according to Puck in v17, these Stonehenge-like structures served as shrines of sorts to the Elves (according to Dark Horse's translation, anyway), and Guts even used it to take refuge from the spectres and incubi. So to see Griffith, a God Hand, appropriate it for his own purposes is...kind of unnerving me. Not only can his army launch an invasion seemingly anywhere in the world, which is already a scary proposition, but it's like nothing is sacred anymore.