Pope Benedict XVI waves in St. Peter's Square in the Vatican in December 2012. Benedict, 85, announced on Monday, February 11, that he will resign at the end of February "because of advanced age." The last pope to resign was Gregory XII in 1415.
Joseph Ratzinger, who became the 265th pope in 2005, poses for a photo while a German air force assistant in 1943.
Cardinal Joseph Ratzinger, right, poses for a picture in Vatican City in June 1977 with fellow cardinals, from left, Cardinal Gappi, Cardinal Tomazek, Cardinal Gantin and Cardinal Benelli. Ratzinger was named cardinal-priest of Santa Maria Consolatrice al Tiburtino by Pope Paul VI in June 1977.
Ratzinger, who was serving as cardinal-priest of Santa Maria Consolatrice al Tiburtino, visits Madrid in 1989.
Ratzinger fills in for Pope John Paul II during the Easter Vigil service in Saint Peter's Basilica in March 2005.
Newly elected as pope, Benedict XVI gestures to the crowd in St. Peter's Square in Vatican City on April 19, 2005.
Benedict meets Prince Albert II of Monaco at the pope's private library in Vatican City in December 2005.
Benedict kisses the altar before addressing the crowds at Jasna Gora Monastery in Czestochowa, Poland, in May 2006.
Benedict waves from under an umbrella as he arrives to lead his weekly general audience in Saint Peter's Square at the Vatican in October 2007.
Benedict speaks at the United Nations General Assembly in New York in April 2008.
Benedict celebrates a Mass at the end of a synod of Catholic bishops in October 2008 at St. Peter's Basilica at the Vatican.
Benedict attends a screening of a movie about his predecessor, Pope John Paul II, on October 16, 2008, in Vatican City during celebrations of the 30th anniversary of John Paul's election as pontiff.
Benedict kneels as he prays in front of Pope John XXIII's tomb in St. Peter's Basilica at the Vatican on October 28, 2008, to commemorate the 50th anniversary of John's election to the papacy.
Benedict talks with bishops in Saint Peter's Square at the Vatican after his weekly general address in November 2009.
Benedict blesses pilgrims as he arrives in St. Peter's Square in his popemobile in March 2010 to meet with young people from Rome and the Lazio region in preparation for World Youth Day.
The pope salutes from his popemobile in St. Peter's Square in March 2010.
Benedict prepares to celebrate Mass at San Giovanni della Croce parish in Rome in March 2010.
Benedict prays on Good Friday in April 2010 at the Roman Colosseum.
Benedict celebrates an open-air Mass in the Terreiro do Paco in Lisbon, Portugal, in May 2010.
Benedict prepares to celebrate a Mass for 70,000 people in September 2011 in Berlin.
Benedict waves to the crowd gathered at the Colosseum in Rome during the Way of the Cross procession on Good Friday in April 2012.
A gust of wind blows Benedict's collar into his face in September 2012 during his weekly address in Saint Peter's Square.
Benedict speaks with Nikolaus Schneider, praeses of the Evangelical Church in the Rhineland, before a Mass at the Augustinian monastery in Erfurt, Germany, in September 2011.
Benedict waves to pilgrims as he arrives at St. Peter's Square for his weekly address in October 2012.
Benedict looks at a chess game with Ivory Coast President Alassane Ouattara during a private audience in November 2012 at the Vatican.
Benedict arrives to lead the Vesper prayer with members of Rome's universities in December 2012 at St. Peter's Basilica.
Benedict clicks on a tablet to send his first tweet from his account @pontifex at the Vatican in December 2012.
Benedict celebrates Mass during a visit to San Patrizio al Colle Prenestino parish on the outskirts of Rome in December 2012.
Benedict blesses members of the ecumenical Christian community of Taize, a group based in Taize, France, in St. Peter's Square in December 2012.
Benedict, accompanied by Grand Master Matthew Festing of the Sovereign Military Order of Malta, right, shakes hands with a woman after the Mass in St. Peter's Basilica to mark the 900th anniversary of the Order of the Knights of Malta on February 9, 2013, at the Vatican.
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STORY HIGHLIGHTS
- NEW: Pope injured himself on a trip, a Vatican spokesman says, but this had no health impact
- The pontiff celebrated his last public papal Mass to mark Ash Wednesday
- Cardinals are expected to hold a conclave to decide on a successor in mid-March
- Benedict's decision to resign on February 28 shocked the Roman Catholic Church
Rome (CNN) -- Pope Benedict XVI addressed parish priests from the city of Rome on Thursday, in what is likely to be one of his final public appearances before his resignation from the papacy at the end of the month.
The meeting with the parish priests focused on Benedict's experiences from the Second Vatican Council, in the 1960s, which examined the Roman Catholic Church's relationship with the world.
Pope's resignation: A challenge for reporters
Benedict, who was greeted by lengthy applause, said it was a "special moment" to sit before the clergy of Rome before his departure.
Benedict, 85, celebrated his last public papal Mass at St. Peter's Basilica on Ash Wednesday, which marked the beginning of Lent.
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He shocked the world Monday when he announced his intention to stand down on February 28, citing the frailty of old age.
He is the first pope to resign in nearly 600 years.
When do you know it's time to go?
A Vatican spokesman, the Rev. Federico Lombardi, did not deny Thursday that Benedict had had an accident on his March 2012 trip to Mexico, but said the injury had no effect on his health or his decision to resign.
Italian newspapers reported that the pope fell and hit his head against a bathroom sink during the trip.
Addressing the faithful Wednesday in his weekly general audience, Benedict said he was stepping down for the good of the Roman Catholic Church and thanked them for their prayers.
"In these days which have not been easy for me, I have felt almost physically the power of prayer -- your prayers -- which the love of the church has given me. Continue to pray for me, for the church and for the future pope," he said.
Read more: Huge challenges await next pope
Vatican Secretary of State Tarcisio Bertone later thanked Benedict for his service.
"All of us have understood that it is precisely the deep love that your holiness has for God and the church which pushed you to this act," he said.
Benedict will hold a final audience in Vatican City's St. Peter's Square on February 27, but the church is not planning a formal ceremony to mark the pope's departure, Lombardi said Wednesday.
The pontiff, born Joseph Ratzinger, will first go to the pope's summer residence in Castel Gandolfo, and then is likely to retire to a monastery and devote himself to a life of reflection and prayer, Lombardi said.
He won't be involved in managing the church after his resignation.
Opinion: A traditional papacy ends with a surprise
The Vatican does not yet know exactly when cardinals will meet in a conclave to decide who will replace Benedict, but if all goes normally, it will probably start between March 15 and March 19, Lombardi said Wednesday.
He had previously said a new pope would be in place before Easter is celebrated at the end of March.
The last pope to step down before his death was Gregory XII, who in 1415 quit to end a civil war within the church in which more than one man claimed to be pope.
Pope's resignation a new angle to a tough news beat
CNN's Vatican analyst John Allen and Hada Messia reported from Rome, and Laura Smith-Spark wrote and reported from London.