On February 24, 1530, Pope Clement VII crowned Charles Habsburg Holy Roman Emperor in the Basilica San Petronio in Bologna. It was the last time a pope would crown an emperor, ending a 700-year-old tradition that began with Charlemagne's coronation on Christmas Day in 800.
Amid increasing power of the Ottoman Empire to the east, the subjugation of the New World to the west, and the rise of Protestantism within Europe itself, the political situation was delicate. Charles could not be crowned in Rome, because Protestant German mercenaries he employed in a conflict with France had sacked the Eternal City three years earlier.
This context informed the planning and execution of the ceremony, which had to conform to tradition but also reflect the political realities of the day. For the newly-crowned Charles V and Pope Clement, the coronation signified a continuation of an idealized, united, Christian European state that had its origins in the Roman Empire itself.