On August 21, 1879, in the small village of Knock in Northern Ireland, an apparition occurred when the Blessed Virgin Mary, Jesus as Lamb of God, St. Joseph, St. John the Evangelist and angels appeared at the village church. In the more than 100 years since then, Knock has become the most visited pilgrimage site in Europe, along with Fatima and Lourdes, with one and a half million pilgrims visiting every year.

More about the apparition in Knock: https://en.wikipedia.org/wiki/Knock_Shrine
A livestream of the Masses is also available at: https://www.knockshrine.ie/watch-live/

The painting of the apparition of Knock is located
in the Knock Parish Church, dedicated to St. John the Baptist