The spiritual tradition of the Franciscans is connecting the with the good work of the sainted founder, Saint Francis, who as you know, fixed three chapels: the third was called the Portiuncula (the Little Portion), dedicated to Saint Mary of the Angels. As you can see, the chapel sits in a large basilica in Assisi. The friars have been at the Portiuncula since early thirteen century. SaintClare made her vows following Palm Sunday in 1212 and where Francis died on 3 October 1226.
grant remission of sins to all who came there. It used to be given only at the Portiuncula but now the privilege extends beyond the Portiuncula especially those administered by Franciscans, throughout the world, to others churches as well.
The Church teaches that a plenary indulgence is a powerful tool for works of mercy and weapon in the living of the Christian life, that is, in our spiritual warfare. A plenary indulgence is the remission of the effects of sin, through the merits of Jesus Christ and the saints, through the Church, of all temporal punishment due to sin already forgiven through the reception of the sacrament of Confession.