Origins and structure
The empire traced its legitimacy back to Charlemagne's coronation as Roman Emperor in 800, and was formally revived in 962 when Pope John XII crowned the German king Otto I. In theory it continued the Roman Empire in the West; in practice it was never a centralized state but a patchwork of hundreds of German-speaking kingdoms, duchies, prince-bishoprics, free cities and knightly estates, each with its own laws and rulers, loosely bound together under an emperor whose real authority varied enormously from reign to reign and region to region.