The Latest on Pope Francis' visit to Poland and World Youth Day celebrations (all times local):

11:45 a.m.

Pope Francis has praised native son St. John Paul II as a "meek and powerful" herald of mercy as well as countless "ordinary yet remarkable people" who held firm to their Catholic faith throughout adversity in the former Communist-ruled nation.

The Argentine pontiff, who had never had set foot in Eastern Europe before this week's five-day pilgrimage, gazed in awe for several minutes at the Jasna Gora monastery shrine's iconic image of the so-called Black Madonna and Child. The faces in the images are blackened by centuries of varnish and candle soot since the artwork became the object of veneration starting in the 14th century.

Then, during an outdoor Mass before tens of thousands, Francis lavished praise on a legacy of steadfast Polish Catholic faith as he urged Poles to hold fast to their faith.

The Mass was held in celebration of the 1,050th anniversary this year of the Poland's acceptance of Roman Catholicism. The baptism of a medieval king in 966 put the nation on course to be part of the Latin-speaking world, setting it apart from Orthodox nations on its borders.

___

9:30 a.m.

Pope Francis is urging today's Poles to stay united, as their nation is divided over such issues as how to view refugees and migrants, especially those who aren't Christians.

During an outdoor Mass before tens of thousands of people, Francis prayed that Poles would have "the desire to leave behind all past wrongs and wounds, and to build fellowship for all, without ever yielding to the temptation to withdraw or to domineer."

Worry about bad weather prompted a last-minute change in his day's travel plans, with the pontiff opting to take a car instead of a military helicopter to Czestochowa. But the gray skies held into the Mass.

Francis will have his first big meeting with the young faithful in a Krakow meadow on Thursday evening.

___

9 a.m.

Pope Francis has made an unscheduled stop at a clinic to visit and pray for comatose Cardinal Franciszek Macharski, an-89-year-old retired prelate who had been archbishop of Krakow.

Marcharski had replaced Cardinal Karol Wojtyla in the post after the latter was elected the world's first Polish pontiff, John Paul II, in 1978.

With John Paul a national hero as well as a beloved saint, Francis on this five-day trip finds himself in a deeply Catholic country that is attached to Czestochowa, where the shrine is located, and where a main boulevard is named after John Paul.

___

Monika Scislowska in Krakow and Vanessa Gera in Warsaw contributed to this report.

___

Frances D'Emilio is on twitter at www.twitter.com/fdemilio