VATICAN CITY (AP) -- Pope Benedict gave thanks for his 80 years of life dedicated to the Church with a special Sunday Mass, a celebration tinged with nostalgia which drew a huge crowd to St. Peter's Square.

Joseph Ratzinger, who would take the name of Benedict as pontiff, was born April 16, 1927, in Marktl Am Inn, a riverside town in the Bavaria region of Germany.

Thousands of pilgrims from Bavaria attended the Mass, and German echoed in the ancient alleys leading to the Vatican as groups streamed to the square.

Benedict told the crowd they were joining him in a reflection of his "not brief" life. Acknowledging their participation, the pope said he was extending, "my most sincere thanks, from the depth of my heart, to the entire Church, which, like a true family, especially in these days, surrounds me with its affection."

He thanked his late sister, Maria, and his retired choirmaster brother, Georg, for being steadfastly close to him.

"I give thanks in a special way because, from the first day, I was able to enter and grow in the great community of believers" in God, Benedict said. He noted that he was born at Easter time, when Christians celebrate in joy their belief in Christ's resurrection.

Right after Benedict's election as pope, his brother expressed worry about the toll that the burdens of the papacy might take on his brother's health. But Benedict's stamina seems to be holding up despite his rigorous schedule.

On Wednesday, he will receive UN Secretary-General Ban Ki-moon at the Vatican, and next weekend he will make an overnight pilgrimage to northern Italy. In early May, he will travel to Brazil, where the traditionally strong Catholic Church is losing some faithful to Protestant evangelical churches.