On ley lines. Can be seen easily in some English countryside, just from the cows lining up.
About them specifically, I've not read as much as I'd like. Inside some ca'er is a spiral of ley-line to which the out-branching ley-lines are in central alignment. So what was later called a hill-fort or castle(dun) was first a man made hill to raise a dirt platform high in middle-earth right physically above the place of the matrix of lines of 'life-force' (magnetic linears between electro-magnetic pressured areas¿) electro-magnetic conduits. Dragons.
For research, a good start is - to read the oldest recorded 'book', from The Natural History Museum London, - co'era lingus -