When Graham Robb made plans to cycle the legendary Via Heraklea, he had no idea that the line he plotted – stretching from the south-western tip of the Iberian Peninsula, across the Pyrenees and towards the Alps – would change the way he saw a civilization.

It was an ancient path that took him deep into the world of the Celts: their gods, their art, and, most of all, their sophisticated knowledge of science. Gradually, a lost map revealed itself, of an empire constructed with precision and beauty across vast tracts of Europe.

You can explore The Mediolanum Mystery from The Ancient Paths by using the map below.

Toggle layers of place names discussed in Part 1 Chapter 3 and Part 1 Chapter 4 of The Ancient Paths, and try drawing circles, lines and polygons for yourself. Please refer to pages 294-296 in The Ancient Paths if you need more technical details.

You can access the raw data and a larger map here.

Download a PDFs of figures 1, 41, 43, 62, 64, 74 and 79 here

The Ancient Paths is available from panmacmillan.com