Do locational fundamentals such as coastlines and rivers determine town locations, or can historical events trap towns in unfavorable locations for centuries? We examine the effects on town locations of the collapse of the Western Roman Empire, which temporarily ended urbanization in Britain, but not in France. As urbanization recovered, medieval towns were more often found in Roman-era town locations in France than in Britain, and this difference still persists today. The resetting of Britain’s urban network gave it better access to naturally navigable waterways when this was important, while many French towns remained without such access.