Pope Francis on Thursday made an unannounced visit to a small makeshift medical center in front of St. Peter's Square where poor and homeless people are receiving free treatment ahead of this weekend's World Day for the Poor.

According to Selene, a young volunteer present when the Pope arrived Nov. 16, “It was absolutely an unforgettable surprise for me, and for all the volunteers serving here,” whom she said are all young Italians.

In comments to CNA, she said she has “no words” to describe the encounter, in which the Pope thanked them for their work, blessed them, and spent time talking with the poor and needy for about 20 minutes.

Pope Francis arrived to the center around 3:45p.m., where he was welcomed by a group of poor people waiting to be seen by specialists.

The center was set up in anticipation of the first World Day of the Poor, which will take place Nov. 19 and is being organized by the Pontifical Council for the Promotion of the New Evangelization.

Open from 9a.m. until 4p.m. every day this week, the center offers patients free visits with doctors who specialize in clinical analysis, cardiology, dermatology, infectious diseases, gynecology, and andrology.

The doctors operate out of small mobile ambulances that patients can go into for a check-up or for a more specialized exam.

After talking and exchanging jokes with the poor and homeless waiting to be seen, the Pope then spoke with nurses from the Italian Red Cross and volunteers with the Confederation of Mercy, who help operate the center.  

Dr. Silvia Rosati said the Pope's surprise appearance was “a beautiful experience, a wonderful experience.”

“We are trying to do the little that we can right now,” she said, recounting how the Pope told them to “continue trying to be as present as possible with the poor, and with our attempt to help people as much as we can with our work.”

Established by Pope Francis at the end of the Jubilee of Mercy, the World Day for the Poor this year has the theme “Love not in word, but in deed.”

In addition to access to free medical exams, the poor and needy participating in the event will attend a  said Mass by Pope Francis in St. Peter's Basilica. Afterward, they will be offered a three-course lunch at different centers and organizations around Rome, including the Vatican's Paul VI Hall.