Same Shape, Different Millennia: Stone Circles in Europe's Open Data

Stone circles are usually thought of as a monument of Neolithic and Bronze Age Britain and Ireland. I test that picture by building one cleaned, de-duplicated catalogue of every stone circle and ship setting in Europe's two large open datasets, OpenStreetMap and Wikidata, and dating each regional tradition from published sources and from radiocarbon dates in the p3k14c database linked to named circles. The catalogue holds 3,451 records in 21 countries. Only 20% belong to the Neolithic and Bronze Age circles of Britain, Ireland, Brittany and south-west Iberia; 62% are Iron Age judge's rings in Scandinavia and Finland, although 95% of the Swedish records come only from Wikidata, so the size of that majority partly reflects what has been digitised. On their published dates, the traditions span 6,400 years, from the Alentejo cromlechs of the sixth millennium BC to the Gothic circles of Pomerania, used to about AD 400. 356 radiocarbon dates link to 43 named circles and broadly agree with the published ranges: 30 of 37 dated circles in Britain and Ireland have a middle date between 3300 and 900 BC. Comparing the closest distance and the gap in time between traditions, some pairs touch in both (Britain and Brittany; Sweden and Pomerania) while others are separated by hundreds of kilometres of sea or more than a thousand years. The data are consistent with at least two separate beginnings of the circle, an Atlantic one in the Neolithic and a northern one in the Iron Age, though they cannot prove reinvention. A terrain test in Britain and Ireland finds a gentle preference for locally high ground with slightly wider views. Interactive version: https://tristan-hotham.github.io/stone-circles/. Data and code: https://github.com/Tristan-Hotham/stone-circles. Blog post: https://blog.tristanhotham.com/2026/10/27/stone-circles/.