CHRONOLOGY: Pope Benedict as pontiff

(Reuters) - Pope Benedict on Sunday ended his U.S trip with a visit to Ground Zero, where he prayed at the site of the felled World Trade Center, and a triumphant Mass for 57,000 at Yankee Stadium.

Here is a chronology of major events since Joseph Ratzinger was elected pope on April 19, 2005.

April 24, 2005 - Benedict is installed as leader of the Roman Catholic Church at an inaugural Mass.

June 10 - Pope attacks the use of condoms to fight HIV/AIDS in his first comments on the disease, saying the Church is leading the battle against AIDS by teaching chastity.

November 29 - In a first major ruling of Benedict's reign, the Vatican imposes restrictions on homosexuals becoming priests.

December 25 - Benedict, in his first "Urbi et Orbi" (To the City and World) message and blessing, urges humanity to unite against terrorism, poverty and environmental blight.

January 25, 2006 - Pope releases first encyclical, called "Deus Caritas Est" (God is Love).

September 12 - Benedict sparks protests from the Muslim world with a speech Muslims say portrayed Islam as a religion tainted by violence and irrationality.

September 17 - Benedict tries to calm Muslim anger over his lecture, saying he was "deeply sorry" about the reaction and that the medieval quotes he used on holy war did not reflect his personal views.

September 25 - Benedict expresses his "esteem and profound respect" for Muslims in a speech to envoys from 20 Muslim countries.

December 1 - Pope ends a sensitive, fence-mending visit to Turkey, praised for visiting Istanbul's famed Blue Mosque and praying there facing toward Mecca "like Muslims."

February 24, 2007 - Benedict condemns genetic engineering and other scientific practices that allow people screen babies for defects.

April 13 - Benedict, in his first book since becoming pontiff, releases "Jesus of Nazareth," a theological treatise on Christ as both God and man.

May 9 - Benedict delivers a strong anti-abortion message to Brazilians at the start of his first visit to Latin America.

June 30 - Benedict calls on China to lift restrictions on religious freedom that "suffocate" the Church and sow divisions among Catholics.

October 11 - Benedict appeals to scientists to stop using human embryos in stem cell research, saying it violates "the dignity of human life."

Feb 5. 2008 - The pope orders changes to a Latin prayer for Jews at Good Friday services by traditionalist Catholics, deleting a reference to their "blindness" over Christ.

March 23 - The pope baptizes Magdi Allam, a well-known Egyptian-born journalist and outspoken critic of radical Islamism, at an Easter Vigil service.

April 15 - The pope arrives in Washington on his first visit to the United States as pontiff.

April 17 - Benedict has a surprise meeting with victims of sexual abuse by priests in an effort to heal scars from a scandal that deeply tarnished the Catholic Church in the United States.

April 18 - In a speech to the U.N. General Assembly, the pope says countries that act unilaterally on the world stage undermine the authority of the United Nations and weaken the broad consensus needed to confront global problems.

April 20 - Pope says Mass at Ground Zero.

(Writing by David Cutler in London and Paul Grant in Washington)