Pope Francis urged Catholics on Friday to "tear down all walls" and spread peace as he marks the 100th anniversary of two children believed to have seen the Virgin Mary.

Pope Francis is the fourth pontiff to make a pilgrimage to Fatima in half a century.
Pope Francis is the fourth pontiff to make a pilgrimage to Fatima in half a century. (TRT World and Agencies)

Pope Francis called for harmony "among all people" on Friday after arriving at Portugal's holy site of Fatima where he was greeted by thousands of pilgrims gathered to mark 100 years since child shepherds had visions of the Virgin Mary.

During his visit, he prayed for an end to wars he said were lacerating the world and urged the faithful to "tear down all walls" to spread justice and peace.

The main purpose of the trip to the central Portuguese town, which receives around 7 million people a year, is a huge open-air Mass on Saturday to declare two of the children saints.

Paul Ames, who is following the story for TRT World, explains the significance of the visit.

Three prophecies

Fatima has become a major holy site since the Virgin is said to have appeared in 1917 to Jacinta, seven, Francisco, nine, and their cousin Lucia, 10.

The Church believes the Madonna gave the children three messages, the so-called secrets of Fatima.

The first two were revealed soon and concerned a vision of hell, seen by believers as a prediction of the outbreak of World War Two, a warning that Russia would "spread her errors" in the world, and a need for general conversion to God and prayer.

The "third secret" intrigued the world for more than three-quarters of a century, inspiring books and cults convinced that it predicted the end of the world.

A long journey

Many pilgrims trekked to Fatima for days on foot – some finishing the last few metres on their knees.

And while the atmosphere was one of joy, emotions ran high and difficult memories bubbled to the surface.

"We are going to pray to Fatima and Pope Francis so that they can intervene for a peaceful solution for Venezuela," said Jose Ornelas, a 59-year-old librarian who came all the way from Caracas, which along with other cities has been wracked by deadly anti-regime protests.

Source: TRTWorld and agencies