145 years ago today, on 21 August 1879, in the small village of Knock in Northern Ireland, an apparition took place in the village church of the Virgin Mary, St Joseph and St John the Evangelist. 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:

https://en.wikipedia.org/wiki/Knock_Shrine