The Vatican announced Monday that Pope Benedict XVI will step down on Feb. 28. While such papal resignations are extremely rare, there are precedents in the two-millennia history of the Roman Catholic Church:
• Marcellinus abdicated or was deposed in 304 after complying with the Roman emperor's order to offer sacrifice to the pagan gods.
• Benedict IX sold the papacy to his godfather, Gregory VI, and resigned in 1045.
• Celestine V, overwhelmed by the demands of the office, stepped down after five months as pope in 1294. Pope Benedict XVI prayed at the tomb of this hermetic pontiff in the central Italian city of L'Aquila in 2009.
• Gregory XII, the last pope to resign, stepped down in 1415 to help end a church schism.