Pope Francis is visiting the Knock Holy shrine in Co Mayo, which is revered by many Irish Catholics.
Maria Casey, marketing and communications manager at Knock Shrine, explains the meaning behind the pilgrimage site.
“Knock Shrine is a special place in Co Mayo in the west of Ireland because of the apparition that took place here in 1879.
“On August 21, an apparition appeared to 15 people from the village of Knock. At the time, Knock was a small, rural village.
“At about 8.30pm, 15 people saw a light coming from the parish church so they made their way over to the gable wall to see what it was.
“They saw the apparition of Our Lady, St Joseph, St John the Evangelist and a lamb.
“They said the apparition lasted for two hours.
“They all recited the rosary, and after the apparition news spread very quickly. Each of those witnesses were asked to give a testimony to a commission of enquiry.
“There was an investigation a couple months after and that’s when people started to descend on Knock – it spread to newspapers across Ireland, England and America.
“People started to come here in the hope of receiving cures, and Knock became synonymous for that. And people came to the spot of the apparition to get some clay or holy water to send to abroad.
“It has developed over the years and it has a very unique story in the sense that it’s the only shrine in the world where the Lamb of God has appeared.
“As well as being a Marian shrine, it is a Eucharistic shrine.
“People have a special affinity with the place.
“It has a beautiful atmosphere and that’s what draws people to it.”