Altar boys in white cassocks snapped photos and parents lifted children out of strollers to catch a glimpse of the pontiff as he arrived in a popemobile at the L'Esplanade des Invalides, a vast expanse of lawn not far from the Seine river.

The crowd sent up a cheer when Benedict opened the Mass by speaking about "beautiful Paris." Aides held the pontiff's ivory colored robes as he ascended the wooden steps toward an altar erected on a canopied platform.

The late-morning Mass is Benedict's only public appearance Saturday before he flies to Lourdes to make a pilgrimage to the shrine which draws millions of pilgrims each year.

Benedict was expected to give a kind of papal pep talk to the faithful at Mass.

Although traditionally Roman Catholic, France has seen a decline in churchgoing in the last decades, with most French skipping the Sunday requirement to attend Mass.

Paris police estimated the crowd at some 220,000 people.

Tens of thousands of faithful, many of them young people, had camped out on the field overnight after hearing greetings from the pope Friday night as he left a prayer service in Notre Dame. He is making a four-day sojourn in France, his first visit to the country since becoming pontiff in 2005.

"It's not every day that we have the opportunity to pray with the pope. We couldn't miss it," said Muriel Amortila, a 47-year-old physical therapist from Normandy who awoke at 3 a.m. with her three children to attend.

On Friday night, Benedict told young Roman Catholics outside Notre Dame that they shouldn't fear spreading their faith. These days in France, with secularism entrenched and Islam growing, that's easier said than done.

Fear, frustration and misunderstanding over religion—not just Catholic—run deep in French society. Last week, three Jewish boys in skullcaps were treated for fractures and bruises after a suspected anti-Semitic brawl that started with one getting hit by a tossed walnut. Benedict met with Jewish leaders on Friday and condemned all forms of anti-Semitism.

France is home to Western Europe's largest populations of Muslims and Jews. Although most French are Catholic at least by tradition, if not in practice, the old yarn is that most attend church only three times in their lifetimes: at their baptism, wedding and funeral.

France also has another religion, "laicite" or secularism, a fervent belief that faith and the state should be kept strictly separate.

Benedict and French President Nicolas Sarkozy, who held talks Friday, spoke publicly of the contribution religion can make to forging an ethical society.

"They say that Catholics in France are fewer and fewer, and less devoted. But you can see here that is not true," said Robert Pavilla, a 58-year-old school groundskeeper, gesturing toward the throngs of people streaming onto the esplanade.

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Associated Press writer Frances D'Emilio in Paris contributed to this report.
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