Croagh Patrick, quartzite peak, west of Westport and south of Clew Bay, County Mayo, Ireland. It rises to 2,510 feet (765 meters) from a plateau 800–1,100 feet (245–335 meters) high. The mountain is said to have been visited by St. Patrick (flourished 5th century), who, according to one authority, began his ministry there. In modern times, Croagh Patrick has become the site of a popular annual pilgrimage on the last Sunday in July, in which many people scale the mountain barefoot. A tiny chapel is situated on the summit.