Pope Francis walked in a solemn Ash Wednesday procession between churches on Rome's ancient Aventine Hill, calling on people to humbly remember their human limits as faithful began their annual penitential Lenten period.

Francis, carrying his pastoral staff, chanted prayers along with other participants during the few minutes' walk down the street. He wore a purple cloak, in keeping with the somber Lenten mood as Catholics spiritually prepare for Easter, which falls on April 5 this year.

The pope lowered his head so a prelate could dab ashes on his head during the ceremony inside St. Sabina's Basilica, a church which dates to the early 5th century. The ashes symbolize mortality.

Then Francis, along with other churchmen, sprinkled ashes on the foreheads of other faithful, motioning the sign of the cross with their fingers as they did so.

The ritual of the ashes was a "reminder of the truth of human existence," Francis said in his homily. `'We are limited creatures, sinners always in need of penitence and conversion."

Almsgiving, prayer and fasting are traditional ways to mark Lent. Francis encouraged church hierarchy, starting with himself, to be humble enough to cry, so that their prayer will be `'ever more authentic and without hypocrisy."

Holy Week ceremonies, beginning with Palm Sunday on March 29, are expected to draw huge crowds of tourists and pilgrims to Rome and the Vatican. They include the Good Friday evening Way of the Cross torch-lit procession at the Colosseum.