VATICAN CITY -- Pilgrims, tourists and Romans flocked to St. Peter's Square on Saturday for Pope Benedict XVI's first Christmas service since becoming pontiff, the start of his busy holiday celebrations.

In a brief appearance hours before the Midnight Mass, Benedict lit a candle in his studio window overlooking the square. He was keeping up the tradition of his predecessor, Pope John Paul II, by delivering a silent Christmas Eve blessing to the faithful below.

The swelling crowd was treated to a view of the Vatican's 100-foot Christmas tree from Austria as they waited for the service to start.

In the early evening, children sang Christmas carols as the Vatican unveiled a Nativity scene with larger-than-life statues.

Cardinal Edmond Szoka, who administers the Vatican city-state, said the creche scene was larger than in the past so people could better appreciate the poor conditions in which Jesus was born.

"It's important to remember that Jesus came to us as a child, but that this child is God," he told the crowd.

The pope's Midnight Mass in St. Peter's Basilica is a Christmas Eve tradition that starts a busy holiday agenda.

On Christmas Day at noon, the pope was scheduled to offer holiday greetings and deliver the "Urbi et Orbi" message -- Latin for "to the city and to the world" -- to visitors in St. Peter's Square.

John Paul used to delight the crowds by delivering holiday wishes in dozens of languages. John Paul also would use the "Urbi et Orbi" message to comment on conditions around the world, often lamenting conflicts, poverty and the excesses of consumerism.

On New Year's Eve, Benedict will preside over an evening prayer service. The following day, he plans to celebrate Mass in St. Peter's Basilica to mark the Roman Catholic Church's World Peace Day.