When St. Francis had his conversion, he was all about repairing churches of God. Probably the most well known was called the Portiuncula or the “Little Portion,” dedicated to St. Mary of the Angels. In truth, the chapel and the surrounding land belonged to the Benedictines .
The Benedictines made a deal with St. Francis, that the Franciscans could use the church for as annual compensation of a basket of fish from the Tescio river — a rent which is continued to be paid until this very day. This was in keeping with the Franciscans’ vow of poverty.
The Benedictines had a good relationship with Francis and the friars. A fraternity lived at the Little Portion in as early as 1211. This precious building became the “motherhouse” of the Franciscans. It is here that St. Clare came on the night following Palm Sunday to make her vows to God in 1212. So in truth, the Order of Poor Clares began here as well. Sister Death also came to Francis at the Portiuncula on Oct. 3, 1226.
Today the Portiuncula continues to be cherished and enclosed in a basilica at Assisi.
St. Francis of Assisi persuaded Pope Honorius III to grant a plenary indulgence to all those who visited the Portiuncula on August 2 and confessed their sins. This indulgence has been extended to all churches, especially those held by Franciscans, throughout the world.
How to Obtain the Portiuncula Indulgence?
This info graphic explains this well.
This video explains the uniqueness of this indulgence in the history of the Church.
