Neil MacGregor discovers how coins reveal the range and diversity of the Holy Roman Empire, with around 200 different currencies struck in the different territories of Germany. It's an extraordinarily immediate and physical way of grasping the complexity and the confusion of the Holy Roman Empire, because every coin represents a kind of sovereignty. To be able to strike a coin you needed to be the ruler in your territory - and every coin speaks of a particular state, with its particular laws and a whole set of traditions. Producer Paul Kobrak.