But the pilgrimage also became a victim of its own success. It made vast riches for the Catholic Church and the people who organised the trips, encouraging corruption and abuse, breeding robbers, beggars and fake pilgrims and the selling of bogus relics.
By 1986, fewer than 2500 people made the trip.
Now, though, the pilgrimage has experienced an extraordinary comeback, driven by what some say is a millennium quest for spiritual values, and helped by initiatives that have declared the route a Unesco World Heritage Site and a European cultural asset.
Last year, 61,418 received their certificate of pilgrimage and in 1999, a Holy Year, the number was 154,613.
"It is becoming increasingly difficult to cope with demand," says Don Javier Navarro, one of six priests who serve at the Ibaneta monastery in Roncesvalles, on the Spanish side of the border, where pilgrims are offered food, shelter and spiritual support.
"Our problem is that there are now so few people taking up the priesthood."
In 1982, Don Javier's records show, 526 people stopped at the monastery. Last year, it was 26,000, and more are expected this year.
Many arrive exhausted and footsore after negotiating the chill, mist-shrouded passes on foot, bicycle or horseback.
Highway robbers are no longer a problem, but the steep mountain road remains harsh. A few months ago, a Frenchman and a Brazilian were found dead from exposure just 2km from the monastery gates, and two other pilgrims have died on the road this year, one from a traffic accident and the other a heart attack.
Every night, as he and his predecessors have done since the monastery was built in the 12th century, the priest gives "the pilgrim's Mass". Before, the prayer was in Latin and addressed to devout Catholics: today, the crowd includes Protestants, even atheists, and Javier's invocations are in Spanish, French, Portuguese, Italian, English and Basque.
The spiritual lure and companionship of the Camino de Santiago seem clear, although the historical accuracy of the shrine is, to put it politely, open to doubt.
The origins lie in a tale that surfaced in the 9th century and provided a rallying point for Christians struggling against Islamic control of Spain.
It said that St James had travelled to Spain after the crucifixion, worked for seven years to convert the country to Christianity and then returned to Judea, where he was killed by King Herod.
His remains were then taken back to Spain by his disciples - or angels, according to a different version - and lay in an unknown location until, in 813, a visionary cleric called Bishop Theodomir was directed to the spot by a star.
Another nagging doubt surrounds the shrine's authenticity, given that the bones at Compostela were removed in 1589 for safekeeping from the marauding English Navy, and subsequently lost. In 1879, it was claimed they had been found again.
The bones were given a papal blessing and installed in the shrine, once again drawing the faithful, peaking on July 25, St James Day.
