Pope John XXI – the only physician who ever became pope – was born on this day in 1277. By birth, this pope was a Portuguese man named Pedro Julião. He studied medicine, theology, logic, physics, and metaphysics. He became the doctor of Blessed Pope Gregory X (famous for attempting to communicate with the Mongols at the time of Marco Polo), and a cardinal soon after that. Pedro Julião actively practiced medicine and wrote manuals on the treatment of diseases, as well as discussions on Aristotelian logic.
Cardinal Pedro Julião was elected pope in 1276. He took the name John XXI, and the seat of the papacy at that time was not in Rome, but in Viterbo. That small town, about 70 kilometers north of Rome, was the official seat of the papacy from 1257 till 1281 (the relocation was largely due to bad relations between inhabitants of Rome and the popes).
John XXI continued his scholarly research even after becoming a pope. Indeed, he was so preoccupied with this that he had a special room built in the papal palace in Viterbo where he could work undisturbed. However, one night, when the Pope was alone, the ceiling of the room collapsed and caused him serious injuries. The Pope died six days after the event.