An exhibit being created for Pope Francis' trip to Philadelphia will honor the pontiff's teachings by offering visitors the chance to acknowledge the challenges in their daily lives.

An artist will build a grotto made of knots near the city's main cathedral. People will be encouraged to write their problems on ribbon or paper, then tie the material to the exhibit.

The idea is to leave troubles behind. Guests can also choose to remove an existing one to help another.

The installation is inspired by the 18th-century painting "Mary, Undoer of Knots," which the pontiff first saw as a young man visiting Germany.

Francis will visit Philadelphia this fall as part of the World Meeting of Families. More than 1 million pilgrims are expected Sept. 26 for a Mass.