Pope Benedict XVI said on Monday he will resign at the end of February.
In a statement released by the Vatican he said he no longer has the strength to fulfill the duties of his office -- becoming the first pontiff since the Middle Ages to take such a step.
The 85-year-old pope said he had noticed that his strength had deteriorated over recent months, saying "I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me".
A Vatican spokesman said Benedict would step down on February 28, leaving the Catholic Church's highest post vacant until a successor is chosen.
Pope Benedict to stand down (0:48)
Feb. 11 - Pope Benedict XVI will step down as head of the Catholic Church on February 28. Travis Brecher reports. ( Transcript )