Graham Robb says that the idea for his latest book, The Ancient Paths: Discovering the Lost Map of Celtic Europe, “arrived one evening like an unwanted visitor”. He was planning a cycling trip along the Via Hereklea, the “fabled route of Hercules from the ends of the earth … across the Pyrenees and the plains of Provence towards the white curtain of the Alps”, when it struck him that the transcontinental diagonal described by the Heraklean Way corresponded exactly to the “angle of the rising sun at the summer solstice” 2,000 years ago. What he had stumbled upon was a “transcontinental masterpiece of sacred geography”, the work of Druids and Druidesses, the priests and scientists of the Celts. The Heraklean Way, it turned out, was the royal road to an understanding of the lost civilisation of Celtic Europe.

This is not Robb’s usual terrain, however—he is best known as a historian of 19th-century France. So I began by asking him if he’d approached the subject with trepidation.

If I’d still been an academic I wouldn’t have been able to write it, because, as you say, it isn’t my period. It reminds me of someone at Queen’s College in Oxford who had a question about the New Testament—I can’t remember what it was; something Jesus had said. So he asked the college chaplain, and the college chaplain said, “Well, it’s not really my period.” But when I was working on my book The Discovery of France, I was drawn backwards in time to the Gaulish period. And it’s nice working on a different period and discovering the different traditions associated with that form of scholarship. That was quite a release. Archaeology seems a much more congenial discipline—they’re not always trying to slag each other off. The only drawback is that lots of archaeologists prefer the spadework and never get round to publishing what they’ve found.

But this book isn’t just a summary of the state of archaeological research into Celtic Europe is it? There’s an argument being made here about the status of myth. You say that it’s an “uncanny characteristic of Celtic myths … that they often turn out to be true”.

It shows how well the Druids’ education system worked that they used memory and verse to preserve their history. But despite the catastrophes that there were in between it did survive amazingly well—especially in Ireland and Wales. It was…

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