PHILADELPHIA – Pilgrims jotted prayers, struggles, and dreams on some 150,000 knotted ribbons at Knotted Grotto, a temporary installation at the Basilica of Saints Peter and Paul in Philadelphia. The grotto consisted of a 20-by-13-foot wigwamlike structure where visitors were invited to write down their intention or prayer request and tie it to the structure, then untie someone else’s ribbon and add it to an interior frame—an act symbolizing that “sometimes you can’t undo your own knots.” In a spontaneous visit to the shrine, Pope Francis blessed the thousands of prayer ribbons prior to an open-air Mass on September 27, 2015.

Commissioned by homeless advocacy group Project HOME in honor of the Pope’s visit, the work took inspiration from the eighteenth-century German painting Our Lady, Undoer of Knots, a Papal favorite. Artist Meg Saligman explains in Upworthy: “Our contemporary interpretation of this tradition is the knotted grotto of Mary clearing pathways for people to help them with their struggle.” The temporary project has a permanent application: The thousands of ribbons are being used to insulate a housing development for the homeless.