Today, pilgrims walk to Santiago and Finisterre for many different reasons. For some, making a pilgrimage to the Holy City is a lifelong dream borne out of religious faith. Others seek a break from daily routines or want to get back to a simpler way of living, and some want to immerse themselves in Spanish history and culture. You needn't be a hard-core hiker to walk to Santiago, as the trails are well-maintained and ubiquitous yellow arrows make them easy to follow and the journey is made easier and more sociable by a centuries-old infrastructure of albergues (pilgrim hostels).

Along the way, you'll pass through a multitude of Spains. You'll see gorgeous Romanesque churches decorated with grotesque gargoyles and elaborate frescoes, ethereal Gothic cathedrals with airy spires and vast interiors, and tiny ermitas (hermitages) tucked into cliff faces. There are colourful, riotous festivals, where you can dance to Galician bagpipes or watch crazy, traditional Basque sports like hoe-hurling. There's spectacular wildlife, too, from the rarely seen wolves and bears that roam northern Spain's mountain ranges, to peculiar, plain-dwelling birds such as great bustards and hoopoes.

Quite how Santiago ended up in a remote northwestern corner of Iberia is a strange and marvellous tale. Santiago, or St James as he's known in English, was one of Jesus' apostles, and after the Crucifixion, he headed to Spain to spread the Gospel. Though he preached as far north as Galicia, he didn't have much luck with the native peoples, and attracted a mere seven converts before turning to head home.

While there's no biblical basis for Santiago's visit to Spain, it is clear that Herod Agrippa had him beheaded in 44AD in Jerusalem, making him the first apostle to be martyred. Santiago's friends managed to sneak his body out from under Herod's nose, and put him on a stone boat headed for northwest Spain without oars, sails or crew. After a week-long journey, the body arrived in Padrón on the Galician coast, where his disciples were waiting. They buried Santiago 20km inland in Compostela, after the local Queen witnessed a series of miracles and converted to Christianity.

Santiago lay forgotten for a good few centuries, while all around him Spain became Christian through rather gradual, more conventional means. The move to Christianity ended abruptly at the start of the eighth century, when Muslim armies crossed over from North Africa, soon conquering most of the Iberian Peninsula and pushing up into central France. Still, pockets of Christianity remained, notably in northwestern Spain.

In 813, a curious Christian hermit followed sweet music and twinkling stars to a remote hillside in Galicia. The bones he found at Campus Stellae (Compostela) were quickly identified as those of Santiago, and the bishop of nearby Iria Flavia sanctified the discovery. Within a few years, Alfonso II, King of Asturias, visited the site, built a chapel and declared Santiago the patron saint of Spain.

Visions of Santiago multiplied, and the saint became instrumental in the fight against the Muslims. His most famous appearance was at the battle of Clavijo, near Logroño, where he rode high above the battle on a white charger, and personally scythed his way through tens of thousands of Moors. This kind of behaviour made him known as Santiago Matamoros (Moor-slayer), to go with his more pacific image as Santiago Peregrino (pilgrim).

The history of the camino

Well before Santiago's time, the ancient Celts had their own version of the camino, following the via lactea (Milky Way) towards the sea at Finis Terrae (Finisterre), the end of the known world and as far west as they could travel without getting their feet wet.

By the ninth century, Christian authorities had seized on the pilgrimage to Santiago as a way to drive out Muslim invaders and to prevent the peoples of northern Spain from falling back on their pagan ways. Local churchmen were also keen on the cash flow that a stream of pilgrims would bring, and their promotion of Santiago de Compostela as a pilgrimage destination was a masterful piece of medieval marketing.

The number of pilgrims rose over the next couple of hundred years, particularly after the Turkish capture of the Holy Sepulchre made Jerusalem unsafe for pilgrims. The French were particularly keen, so much so that the main route over the Pyrenees from St-Jean-Pied-de-Port and across Spain is called the camino francés.

In 1189, Pope Alexander III declared Santiago de Compostela a Holy City, along with Rome and Jerusalem. Under his edict, pilgrims who arrive during Holy Years (when the Día de Santiago, July 25, falls on a Sunday) can bypass purgatory entirely, while those arriving in other years get half their time off.

It wasn't all voluntary penitence; sometimes people were sentenced to walk to Santiago as punishment for a crime, although wealthy convicts could get around this by paying someone else to walk the pilgrimage. Other pilgrims went on behalf of their villages in an effort to get rid of plagues, floods or locusts, or as an excuse to see the world in the days before package holidays.

Churches and pilgrim hospices sprung up along the camino, often built on the site of miracles. Their walls provided havens from a dangerous and arduous outside world, where wolves and bandits thwarted the faithful.

The stream of pilgrims peaked in the eleventh and twelfth centuries, when about half a million people made the pilgrimage and when many of the towns and cities along the camino were built. French pilgrims of this time may well have been guided by the Codex Calixtinus, a twelfth-century travel guide usually attributed to Aymeric Picaud, a cantankerous French monk with bile-filled views about almost all the people he met and most of the land he walked through.

The number of pilgrims dropped off once the Christian reconquest was complete, and had fallen considerably by the time that Domenico Laffi, a seventeenth-century Italian pilgrim, wrote his guide to the camino francés. The steady decline continued through the eighteenth and nineteenth centuries, and by the mid-twentieth century only a few hardy souls walked the camino.

The camino today

Although the camino had dropped off the world tourism radar, it wasn't entirely forgotten. Santiago remained the patron saint of Spain, and local people were still able to trace the route of the camino through their villages. In one of these villages in the 1960s, Don Elias Valiña, the parish priest at O Cebreiro, began a meticulous labour of love that eventually became El Camino de Santiago, the camino's first modern-day guidebook. By the 1980s, the camino's popularity had soared: in 1982, Pope John Paul II became the first pontiff to visit Santiago de Compostela, then in 1987 the European Union declared the camino Europe's first Cultural Itinerary, and UNESCO followed suit in 1993, adding the camino to its World Heritage list.

Today's pilgrims rarely make the complete journey from their homes to Santiago and back, and most prefer to follow one of the standard, well-marked routes through Spain or France. Some pilgrims walk the via de la plata from Sevilla or the camino inglés from A Coruña, but the vast majority join the camino francés at some point between France and Santiago.

Any pilgrim who walks the last 100km to Santiago can apply for a compostela (a certificate recognizing the completion of the pilgrimage) from the authorities in Santiago de Compostela. The number of pilgrims travelling the camino peaks during Holy Years: 150,000 people reached Santiago in 1999, and future Holy Years are likely to see even more pilgrims. Even in other years, about 60,000 people follow the camino; more than half are from Spain, and most of the rest are European or from the Americas.

Some pilgrim traditions have survived into the modern era. Many pilgrims walk with the aid of a tall staff and wear a scallop shell attached to their pack or person, mimicking statues of Santiago Peregrino. The beaches of Galicia are awash with scallop shells, and medieval pilgrims would often collect one as a souvenir of their journey; scallop symbols are also ubiquitous along the route, adorning concrete camino markers, churches, and houses along the way.