President Mary Mc­Aleese will leave Ireland early this week to join pious travellers from all over the world on the Camino de Santiago de Compostela pilgrimage.

The 780km (485 miles) pilgrimage, known in English as the "Way of St James", traditionally begins in the Pyrenees mountain range of the Spanish-French border and ends at Santiago's cathedral where the faithful believe the remains of St James the Apostle lie. Many travellers join the pilgrimage at various points in the journey.

The cathedral has drawn millions from around the world since the Middle Ages.

Some who make the journey today still wear the traditional garb of cape, long staff and carling felt cap adorned with scallop shells, the symbol of the saint which can be found all over the city.

A spokeswoman for McAleese confirmed that the president was taking part in the pilgrimage. "It's a private holiday she's taking with some members of her family so we would not be commenting on it. Her next public engagement is on 20 April," the spokeswoman said, but could not comment on whether any security personnel were accompanying the president.

There are a number of pilgrimage routes to Camino de Santiago de Compostela. Often, it began at a person's home and ended at the pilgrimage site. However, a few main routes have developed.

During the Middle Ages, the pilgrimage was extremely popular. But the Black Plague, the Protestant Reformation and political unrest in 16th century Europe resulted in its decline. By the 1980s, only a few pilgrims arrived in Santiago annually.

Since then, the route has attracted a growing number of modern day pilgrims from around the globe.

The 'compostela' is a certificate of accomplishment given to pilgrims on completing the walk. To earn the compostela walkers need to travel a minimum of 100km.

In practice for walkers, that means starting in the small city of Sarria, which has good transportation connections. The president's spokeswoman declined to comment on what point McAleese was joining the pilgrimage.