Fatima © Francisco Gomes
In 1917, the Virgin Mary allegedly appeared above an oak tree and spoke to three peasant children in the valley of Cova da Iria, 79 miles (127km) north of Lisbon. The children claimed to have seen the apparition on five different occasions, and the spot has now become one of the great pilgrimage shrines of the world, known as Fatima. Between May and October, the 13th day of every month is pilgrimage day, when hundreds of the faithful gather in a square twice the size of St Peter's in Rome before the Chapel of the Apparitions. The original oak tree is gone, but has been replaced by a simple white column inside a basilica, which is flanked by statues of the saints.