Robb believes that modern historians have systematically underestimated the intellectual achievements of the Celts and have devalued their accomplishments. He points to the widespread dismissal of rhomboid Celtic four-sided enclosures as “irregular” even though they can be inscribed within an ellipse, and he also argues that the Celts must have used well-built gravel roads in order to support the heavy wagons they are known to have built. He suggests that archaeologists attribute to the Romans roads originally constructed by the Celtic peoples from Gaul to Scotland.
Here is where Robb begins to exceed the evidence, according to reviewers. Robb argues that Celtic enclosures were purposely made in rhombus shapes because they were constructed within a symbolic ellipse meant to represent the path of the sun. There is, of course, no evidence to indicate that the Celts viewed the sun’s path as elliptical, or that the buildings were intended as solar structures.
Robb, however, makes some interesting observations that immediately recall the more outlandish claims of the alternative historians. He suggests that the Celts organized their settlements and structures according to an elaborate grid created through astronomical alignments. Here, I think, he has something interesting to say. Alternative historians have been very big on imagining a similar grid constructed along fictional “ley lines” and at the site of “energy centers.” Instead, Robb suggests that the Celts used a complex system of trigonometry based on the observed position of the rising sun at the winter solstice, the path of which they marked on the ground of Iberia as the Via Heraklea. It was later covered over and superseded by the Roman Via Augusta. This is interesting, though I am not sure what proof he has that the Via Heraklea predates the Greco-Roman (or Phoenician-Carthaginian) occupation of Iberia.
He also believes he’s found evidence of “shouting stations” used to relay news across the Celtic world, which should not be terribly controversial since Caesar (Gallic Wars 7.3) recorded the existence of such a thing when he saw how fast news spread when Genabum was attacked:
The report is quickly spread among all the states of Gaul; for, whenever a more important and remarkable event takes place, they transmit the intelligence through their lands and districts by a shout; the others take it up in succession, and pass it to their neighbors, as happened on this occasion; for the things which were done at Genabum at sunrise, were heard in the territories of the Arverni before the end of the first watch, which is an extent of more than a hundred and sixty miles. (trans. W. A. McDevitte and W. S. Bohn)
We know that the Neolithic and Bronze Age peoples of the Celtic lands had elaborate sacred landscapes that were composed of structures aligned with one another and with the sun and the moon. Stonehenge and its surroundings, including Woodhenge, demonstrate this sufficiently. It’s not impossible that Roman-era Celts continued to settle along favorable paths dictated by solar alignments. Yet, the reviewers I have read make plain that Robb’s case is circumstantial and not proved. Here’s Tom Shippy writing in the Guardian:
Too many coincidences, furthermore, erode belief rather than reinforcing it. Culloden Moor was fought in 1746 on a line bisected by the Dinas Emrys meridian, where King Lludd buried the dragons. But one doubts whether any of Bonnie Prince Charlie's men knew that. The summer solstice line from Dinas Emrys takes you straight to Camelot – Camelot theme park, that is, now closed. I doubt Excalibur ever was thrown into Martin Mere close by, even if there is a local legend about it. One has to be aware, as Robb admits, of "the ruthless ingenuity of the unconscious mind".
Robb would inspire more faith in his conjectures if he were not so extravagantly speculative about the Druids and their training. There are absolutely no original sources on this aspect of Celtic society (which according to the Romans had some sort of prohibition against writing their teachings down). Robb is too ready to offer up imaginings of the educational system that must have produced the people capable of the sophisticated feats of geography he can’t prove they performed in the first place.
I’m not sure what to make his claims; some are almost certainly far beyond what the evidence supports, but I think there’s probably merit in at least some of the archaeoastronomy.