Author is a mystery monger; does not like reasonable explanations and wants things to be more mysterious. Relies on opinions of disreputable commentators instead of archaeologists. No references for some of his "scientific" claims. Makes sure to tell you when geomagnetic readings he took were wacky even when he does not investigate why or use controls. Full of a lot of nonsense and some misinformation. Missing plenty of more interesting places. Too old now - the inscribed stones are probably eroded. I do not recommend this; there are plenty of better books on weird places.