MARIAZELL, Austria - Pope Benedict made a pilgrimage Saturday to a famous shrine to the Virgin Mary, where he planned to celebrate an open-air mass for more than 30,000 faithful and make a case that faith is still a force for good in Europe.

The Pope was taken by car to Mariazell, about 150 kilometres southwest of Vienna, after more poor weather on the second day of his Austria visit prompted organizers to cancel plans to bring him there by army helicopter.

The Archdiocese of Vienna said 33,000 believers were ticketed for the event, and that scores from Eastern Europe - including 70 bishops - were among the crowd, which packed a rain-slicked, fog-shrouded field.

A ripple of excitement went through the crowd as the Pope arrived and was greeted by Chancellor Alfred Gusenbauer and other dignitaries. But the atmosphere was tinged with sadness as word spread that an 83-year-old Austrian man who had hoped to glimpse the Pope had suffered a fatal heart attack.

Although there have been no visions of Mary at Mariazell, it has drawn millions of pilgrims over the centuries, and Benedict said the 850th anniversary of its founding was "the reason for my coming."

Security was heavy for the Pope's visit, with more than 3,500 police officers and soldiers and 50 aircraft deployed to protect him. The Interior Ministry said the measures were taken even before this week's thwarted terrorist plot in Germany.

On Friday, Benedict acknowledged Europe's tragic past and warned of its uncertain future as he honoured Jews killed in the Holocaust, and urged the continent to accept its Christian heritage.

He said abortion must never be considered a human right, urged European political leaders to encourage young married couples to have children and said the continent's greying population "must not become old in spirit."

"Europe cannot and must not deny her Christian roots," Benedict declared, saying that Christianity has "profoundly shaped this continent."

During his three-day pilgrimage, which ends Sunday, the Pope is reaching out to disillusioned believers in this central European land, once the centre of a Catholic-influenced empire and now a wealthy but small country that has seen considerable dissent against the church.

In a Friday evening address to Austrian officials and diplomats in the former imperial Hofburg Palace, Benedict spoke of the "horrors of war" and the "traumatic experiences of totalitarianism and dictatorship" that Europe has undergone.

The Pope defended the vitality of Christianity today, saying Christians throughout history have been examples of "hope, love and mercy."

In his condemnation of abortion, Benedict said he was speaking out "for those unborn children who have no voice."

He also urged Europeans to ensure humane care of the elderly, assailing "actively assisted death," a reference to euthanasia and assisted suicide.

Benedict's visit concludes Sunday with a Mass at Vienna's St. Stephen's Cathedral and a visit to the Heiligenkreuz abbey outside the capital.