'7 Days' looks at pilgrimages to Croagh Patrick, Co. Mayo, the reasons for participating in the pilgrimage and the types of people that do it. According to legend Saint Patrick climbed Croagh Patrick and fasted for 40 days and 40 nights.

Bill O'Herlihy, along with 15,000 other pilgrims, visits "The Reek" as it is commonly known on National Pilgrimage Day, which falls on the last Sunday of July each year.

Croagh Patrick is 2,510 feet high, almost 3 miles from base to peak, and takes 3 hours to climb to the top. For many, this all night vigil of pain and endurance represents the roots of their religion - Christianity and the Cross and the "Suffering Irish".For 11 hundred years, men and women have climbed Croagh Patrick with a primitive and purging faith.

The film shows young and old climbing the mountain booted or bare foot in wet, cold and blustery conditions. According to folklore, St. Patrick climbed the mountain and fasted for 40 days and 40 nights.

Another interpretation says that the pilgrimage emerged from a Christian adaptation of a pagan festival. For many, it is now a personal pilgrimage and mass at the top of the reek marks the sacrifice made by the pilgrims.

The meanings assigned to the pilgrimage are many and varied and include: penitential exercise, a physical challenge, a tradition, and a way to pass the night.