The coronation of Charlemagne as Holy Roman Emperor, in Rome.

Charlemagne was King of the Franks from 768, King of the Lombards from 774, and Emperor of what is now known as the Carolingian Empire from 800. He united most of Western and Central Europe, and was the first recognised emperor to rule from the west after the fall of the Western Roman Empire approximately three centuries earlier. Charlemagne's reign was marked by political and social changes that had lasting influence on Europe throughout the Middle Ages.

The Holy Roman Emperor, originally and officially the Emperor of the Romans during the Middle Ages, and also known as the Roman-German Emperor since the early modern period, was the ruler and head of state of the Holy Roman Empire. The title was held in conjunction with the title of King of Italy from the 8th to the 16th century, and, almost without interruption, with the title of King of Germany throughout the 12th to 18th centuries.

December 25 is the 359th day of the year in the Gregorian calendar; six days remain until the end of the year.