Pope Francis made an unscheduled stop at the Mary, Undoer of Knots Grotto in front of the Cathedral Basilica of Saints Peter and Paul.
He was greeted by Sister Mary Scullion of Project Home and volunteers.
"Oh my God," Scullion said, overwhelmed with emotion. "I am so happy for all of us."
The pope's visit lasted minutes.
As he approached the entrance to the grotto, Scullion's friends pushed her through the security line of secret service and police. She stepped forward and hugged the pope.
The pope asked for her prayers she said.
"This meant the world to us, said Scullion. "Especially to the people whose knots he blessed."
Scullion presented a knotted stole woven by Lori Lasher who used hair from 14 different animals. She took the hand-spun wool into soup kitchens, prisons and mental health facilities for people to tie knots and wrote their prayers in a journal for the pope to read.
That project, and the more public prayer grotto outside the Center City cathedral, took months to complete.
It has only been on display for a month and has about 100,000 prayers, written on strips of cloth.
Scullion said she asked the Pope to bless the knots and to bless their struggles.
"Pray for me," he asked her. He then said a private prayer at the grotto.
The surrounding crowd called his name, cheered, and waved flags.
Scullion said her tears were that of gratitude. She was grateful Bishop Chaput, who helped make the "visit and blessing" a reality.
"I will remember this forever," Scullion said.
What you might not also know: Alexander, of Center City, has written three Holocaust musicals, and takes inspiration from human struggles and spiritual stories of all stripes.
Alexander was inspired to write a song, "Help us, Mary," released Saturday for the pope's arrival in Philadelphia.
"The whole concept of problems being knots to be untied really resonated for me," she said. "Also, I just love this Pope so much!"
She enllisted her husband, Burnell Yow, to create a video of Donnie Hammond, a local actress and singer. They filmed it at St. Raymond of Penafort, which is Hammond's church.
Saligman has included the video at the grotto installation - you can hear it playing if you walk over to the painting of Mary, which Pope Francis did Sunday afternoon before celebrating Mass.