Cardinals have been meeting in secret conclaves to elect new popes for centuries: the practice of locking them in derives from a bid to prevent corruption and force electors to vote quickly.
The conclave, named after the Latin phrase meaning "with key", first turned into a lock-in eight centuries ago amid frustration over scandalous months of dilly-dallying by cardinals unable or unwilling to come to a decision.
Here are some of the most bizarre or dramatic conclaves in history:
-- In 1241, when cardinals gathered to elect Gregory XI's successor dragged their feet, the head of Rome's government locked them in a dilapidated building and refused to clean the latrines or provide doctors for those who fell ill.
According to Frederic Baumgartner and his "History of Papal Elections", it was only "following the death of a cardinal, who was allegedly tossed into a casket before he was dead, and a threat from the Romans that they would exhume the dead pope's corpse and have it make decisions," that the cardinals gave in.
-- In 1268, cardinals who had dithered for more than a year after Clement IV's death were locked in the papal palace at Viterbo near Rome and fed only bread and water. When this failed to speed up the process, protesters tore off the palace's roof -- apparently after an English cardinal said that without it the Holy Spirit could descend unhindered -- leaving the electors exposed to the weather. A decision finally came in 1271, after 33 torturous months.
-- The newly elected Gregory X decreed in 1274 that cardinals would have to meet within 10 days of the pope's death and be cloistered in spartan conditions until they produced a successor. He also ruled that they could receive no income during the conclave -- a blow to cardinals used to enjoying irresistible power and financial rewards from running things during the interregnum.
-- One of the earliest and most infamous conclaves was in 532, following the death of Boniface II. It was full of "intrigue, chicanery and corruption... (including) large-scale bribing of royal officials and influential senators," according to P.G Maxwell-Stuart in "Chronicle of the Popes." Eventually, an ordinary priest -- Mercurius -- was chosen as a compromise and swapped his pagan name for John, becoming the first pope to change his name once elected.
-- In 1059, Nicholas II moved to block meddling from outsiders by giving cardinals sole authority to choose pontiffs; until then, members of the clergy and Roman nobility had been allowed to take part. However, the ploy failed to prevent external vetoes on candidates from the likes of the Holy Roman Emperor.
Baugmartner notes how in 1549 Emperor Charles V dispatched a letter warning electors that his many spies would report "when you urinate in this conclave."
-- In 236, cardinals undecided as to who to vote for elected a lay bystander. Fabian had come to Rome after the death of Pope Anteros and was present during deliberations on a successor. According to Eusebius, a Church historian of the era, "Suddenly, they say, a dove flew down and settled on his head... At this, everyone, as if moved by a single divine inspiration, eagerly and wholeheartedly called out that Fabian was worthy." The blessing was a mixed one for Fabian, who died 14 years later a martyr, persecuted by Emperor Decius.
-- A similar fate befell a simple hermit in 1294. Pietro del Morrone had been a Benedictine monk, renowned for renouncing worldly goods for a barren life in a mountain cave in the Abruzzo region in central Italy. When he wrote to the cardinals after the death of Pope Nicholas IV in 1292, urging them to get on with electing a successor, they chose him. Pietro became Celestine V, but resigned after five months in the hope of returning to his mountain cave. His successor had other ideas, and he was locked up in a tower, where he died.