Santiago de Compostela in Spain was one of three major holy places in medieval Europe with Jerusalem and Rome. This place was devoted to Saint James(Santo Yacob), one of the Apostles, because the cadaver of Saint James had been transported from Jerusalem and discovered in early middle ages. With this miraculous history, the pilgrimage to Santiago started about 10th century. The Catholic church tried to expand their influence by the crusade against Muslims, who dominated most of the Iberian peninsular at that time. For recruiting the crusade, the Pope Calixtus II ordered to write the book Codex Calixtinus, containing the Pilgrim’s Guide to Santiago de Compostela. This book shows the prcess of the establishment of Roman Catholic Church in western Europe. The history of saints and saints’ relics accounted for almost half of the book. This shows that the Apostles and the Virgin Mary substituted for the local saints, who had replaced the pagan divinities in early middle ages. The pilgrims were the carriers of more general saints and their relics along the road of pilgrimage. The book Codex Calixtinus shows this process. At the same period, along the road of pilgrimage, the tympanum sculpture of the cathedrals appeared for the first time in 12th century. In the sculpture Last Judgement, Jesus was portrayed as big figure in the center, and beside Him the Apostles as small figures stood. Under the foot of Jesus, many saints expressed as more small figure. This sculpture represented the hierarchy of the Catholic Church. So the pilgrimage contributed to the spread of the tympanum sculpture and eventually to the establishment of the Roman Catholic authority.