In 1122 Pope Calixtus II gave Compostela the privilege of granting a plenary indulgence to those who visited the shrine of the Apostle in the years when the Saint’s day fell on a Sunday. This is recorded in the Bull, Regis Aeterni, issued by Pope Alexander III in 1179.
In the years in which the Feast of St. James (25th July) falls on a Sunday, that year is celebrated as a Holy Year. Therefore there is a Holy Year every 6, 5, 6 and 11 years. The last Holy Year was in 2010 and the next is in 2021. During Holy Years there is a considerable increase in the numbers of pilgrims to Santiago, who may enter the Cathedral by the “Holy Door” which is only opened during that year.