In the western part of Ireland, in County Mayo, there is Mount Saint Patrick (Croagh Patrick 764 m above sea level)

An excerpt from the article 39 facts about Ireland

It is a pilgrimage site associated with the cult of the patron saint of Ireland. According to beliefs, the saint spent 40 days there in 441, praying and abstaining from eating during Lent. On this occasion, he supposedly drove away all the snakes from the island and also used the St. Brigid's Bell–evil spirits taking the form of birds, and defeated the old god Lugh.

About 60.000 people make a pilgrimage here every year.