When was Charlemagne crowned empire?

Charlemagne was crowned Emperor of the Romans on December 25, 800 AD, by Pope Leo III in St. Peter's Basilica in Rome. This event marked the revival of the title of emperor in Western Europe and symbolized the fusion of Roman, Christian, and Germanic elements in his reign. Charlemagne's coronation is often seen as a pivotal moment in the establishment of the Holy Roman Empire.