A great, sprawling, ancient and unique entity, the Holy Roman Empire, from its founding by Charlemagne to its destruction by Napoleon a millennium later, formed the heart of Europe. It was a great engine for inventions and ideas, it was the origin of many modern European states, from Germany to the Czech Republic, its relations with Italy, France and Poland dictated the course of countless wars - indeed European history as a whole makes no sense without it. In this work, Peter H. Wilson explains how the Empire worked. It is not a chronological history, but an attempt to convey to readers why it was so important and how it changed over its existence.