Pope Benedict XVI

Pope Benedict XVI celebrates his 80th birthday on Monday, April 16. Click on the following pictures for a look at his path to the papacy and the impact he has had.

Born on April 16, 1927, Joseph Ratzinger grew up surrounded by World War II. Though obligated to join the Hitler Youth, Ratzinger later said he left the group as soon as organizers stopped requiring him to attend. Early in his life, Ratzinger decided to follow the path of the church and even as a boy expressed his wish to become a cardinal.

Pope Benedict XVI, then still known as Father Joseph Ratzinger, 25, celebrates mass in the mountains of Ruhpolding in 1952, one year after being ordained.

Just four years after he was ordained, Ratzinger became a theology professor at the University of Regensburg. A respected member of the staff, he went on to become the university's vice-president and is known as one of the church's most well-regarded theologians.

Ratzinger was known as a progressive member of the church during the Second Vatican Council, which ended in 1965, but the student protests of the late 1960s reportedly made him more conservative. In 1981, Pope John Paul II called then Cardinal Ratzinger to Rome, appointing him to Prefect of the Congregation for the Doctrine of the Faith.

Even before being chosen pope, Ratzinger had long been a familiar face in the Vatican. Whether considering matters of the church or meeting with the public, many felt his influence could not be overemphasized.

As the Catholic Church's top official in dogmatic issues, Ratzinger was one of the most influential voices in the Vatican. His position meant he often met with Pope John Paul II and advised his predecessor on matters of faith. As John Paul aged, many saw Ratzinger as the church's driving force.

Ratzinger was already considered a favorite in the conclaves held in 1978, after the death of Paul VI, and then of John Paul I, who died after just 34 days in office. But he supported John Paul II in 1978, and then became pope in his third conclave.

Cardinal Ratzinger was called on to celebrate John Paul II's funeral mass on April 8, 2005. Later it would be up to Ratzinger to lead the deliberations to choose John Paul II's successor.

"We have a pope:" The white smoke over the Sistine Chapel signaled the election of a new pope on April 19, but the thousands in St. Peter's Square and millions around the world had to wait a little longer to find out that German Cardinal Joseph Ratzinger had become the 265th man to lead the Catholic Church.

The German flag could be seen all over St. Peter's square as tourists celebrated the election of a German to the papal throne April 19, 2005.

Pope Benedict XVI celebrates mass in the Sistine Chapel for the first time on April 20, 2005. He pledged to continue the liberalizing reforms of the Second Vatican Council and to work to unify all Christians, as he outlined goals following an election that sent a signal the Catholic Church was intent on sticking to tradition as it confronts 21st-century problems.

Newly chosen pontiff Benedict XVI emerges from the Vatican to meet the thousands assembled outside. In his first blessing as pope, the 78-year-old asked for the prayers of those around the world.

Long the guardian of doctrinal orthodoxy, Ratzinger wrote many books on theological issues as well as addressing the church's place in the world. He urged readers to maintain traditional Catholic values concerning abortion, birth control and women in the church as Catholicism went through a number of difficult phases.

Pope Benedict travelled to the site of the Auschwitz concentration camp in Oswiecim while visiting Poland in May 2006.

In September 2006, Pope Benedict came to Germany, paying a visit to his home town of Martkl in Bavaria. The pontiff is seen here with his brother Georg Ratzinger.

The pontiff visited Istanbul's Blue Mosque, accompanied by Muslim clerics, during a 4-day trip to Turkey. It was the second papal visit to a Muslim place of worship, after Pope John Paul II's historic stop in a Syrian mosque in 2001.

"To the city and to the world:" The pope gave his annual Easter address from the balcony of St. Peter's Basilica at the Vatican on Sunday, April 8, 2007. He decried suffering in much of the world and read out a litany of troubling current events, saying he was thinking of the "terrorism and kidnapping of people, of the thousand faces of violence which some people attempt to justify in the name of religion, of contempt for life, of the violation of human rights and the exploitation of persons."

The Austrian federal post office issued this stamp in honor of Pope Benedict's 80th birthday.