Reek Sunday aka Domhnach na Cruaiche aka Garland Sunday is a yearly day of pilgrimage in Ireland which has been held some 1500 years.
On the last Sunday in July, pilgrims climb the holiest mountain in Ireland. Croagh Patrick is in County Mayo. The climb takes about two hours. The descent take about one and a half hours.
The climb is held in honour of Saint Patrick who is said to have spent forty days fasting on the mountain in the 5th century.
Some of the pilgrims hold masses in a chapel at the summit. Some climb the mountain barefoot, as an act of penance, and some carry out 'rounding rituals', which were formerly a key part of the pilgrimage.
These involve prayers while walking sunwise around features on the mountain.
It was traditionally held that pilgrims made the climb after sunset.