The secret vote that elected Pope Gregory X lasted from November 1268 to September 1271. It was the first example of a papal election by “compromise,” after a long struggle between supporters of two main geopolitical medieval factions — those faithful to the papacy and those supporting the Holy Roman Empire.

Now that Pope Francis has been laid to rest, there's a renewed fascination with the centuries-old traditions of the Vatican. Eyes are turned toward the secretive process that will determine his successor,