On Christmas Day, AD 800, Charlemagne, King of the Franks, entered St. Peter’s basilica for mass… and ended up being crowned emperor by Pope Leo III. It’s not clear to historians if Charlemagne knew it would happen or not. It was the first time a Pope claimed the authority to crown a secular ruler.
When Leo crowned Charlemagne that Christmas Day, he knew he would be making history. So why would the Pope choose this basilica in Rome as the place to assert his authority? The basilica was first built by Emperor Constantine in the 4th century over the traditional location of Apostle Peter’s tomb. Peter, and this location, came to be intricately tied to the Popes because of a statement by Jesus in the book of Matthew. Those words of Jesus’ were interpreted by church leaders as giving Peter and his successors absolute authority over the church. Those biblical verses and their interpretation have had countless implications, including making this particular spot in Rome exceptional. After standing for over a thousand years, the original St. Peter’s was in disrepair, and a new structure was commissioned to be built in its place. That task fell to leading Renaissance artists and architects, including Michelangelo, who served as one of the chief architects. Completed in 1626 the basilica remains the largest church building in the world in terms of volume, capable of holding over 60,000 people. And that spot where Charlemagne was crowned emperor by Pope Leo II is now encircled high above with the words from the Gospel of Matthew, written in Latin: “You are Peter, and upon this rock I will build my church…and I will give you the keys to the kingdom of heaven.”