Pilgrims' progress: a new pilgrimage church for one of Italy's best loved saints provides a huge gathering space for the faithful that combines grandeur and a sense of the numinous.

In a country particularly in thrall to the cult of sainthood, St Padre Pio stands as one of Italy's most modern and best-loved saints. Canonized with great ceremony by the Pope in 2002, Padre Pio was a Capuchin monk famous for his bleeding stigmata, miraculous healing powers and the rather enviable ability to be in two places at once. When he died in 1968, his remains were interred in the church of his home village of San Giovanni Rotonda in Puglia, the impoverished and remote province that extends down the south-east side of the Italian peninsula. This rapidly became a site of modern pilgrimage-B million people visit each year, making it the second most popular shrine in Christendom after the Basilica of Our Lady of Guadaloupe in Mexico -- but it also spawned a familiar growth industry of cheap hotels, souvenir shops and a vast acreage of kitschy Catholic trappings. The modest church of Santa Maria della Grazie, Padre Pio's current resting place, has long been unable to cope with this influx, so it was decid ed, with Vatican approval, to construct a new basilica, capable of accommodating 7200 people, with room for an additional 30,000, who might swell the capacity on feast days, standing outside in an adjoining piazza.

In 1991 Renzo Piano got the job, through a mixture of charm and obstinacy on the part of the Capuchin monks, who faxed Piano's office a personal blessing from St Luke's gospel ('In your patience possess ye your souls') each day for three weeks until eventually he agreed to accept the commission.

The site lies in a gentle natural amphitheatre near the top of a hill overlooking the town, not far from the Capuchin monastery and existing church, from where Padre Pio's remains will be removed and re-interred in the new basilica when it opens later this year. A new winding approach road will draw cars and pilgrims away from the town centre below, and groves of newly planted cypresses around the site will enhance a sense of seclusion, despite the great throngs of visitors.

The church was one of the last collaborations between Piano and engineer Peter Rice and reflects Rice's interest in using stone, a traditional structural material, in radical new ways. Here, 21 arches made of blocks of pale Apricena marble break free from the more usual confines of walls to form a series of dramatic free-standing supports. Arranged in a radial pattern, the stone arches are crowned by a shallow domed roof clad in panels of green pre-patinated copper. The most massive arch is 16m high with a span of 50m, credentials that might make it the largest stone arch ever built. Piano was concerned that such a huge interior should not be reduced to the soulless functionalism of an aircraft hangar or sports hall, so the great muscular arches break up and animate the space. Like the builders of Gothic cathedrals 1000 years ago, the architects made use of contemporary technology to push the boundaries -- structural calculations were computerized and special digital machines were used to design, shape and cu t the 40 or 50 stones that make up each arch. As Piano notes, 'Technical virtuosity is not an end in itself, but meets the needs of a precise, formal choice'.

In some ways, the building is six churches conflated into one. Pilgrims are always aware of the altar at the heart of the spiralling, shell-like plan, but are not necessarily aware of the entire space. Shafts of direct sunlight are carefully choreographed to shine down directly onto the altar, their intensity emphasized by the sepulchral semi-darkness of the surroundings. A simple glass wall separates the church from its huge parvis, dematerializing the boundary between interior and exterior. Paving in the piazza also extends into the church, so that it becomes, in effect, an open house, a notion as ancient as the liturgy itself, gathering hordes of weary pilgrims into the bosom of the divine.

RELATED ARTICLE: Architect

Renzo Piano Building Workshop, Genoa

Structural engineers

Ove Arup & Partners, Favero & Milan, C.O.R.E. Ingegneria

Services engineer

Manens Intertecnica

Acoustics consultant

Muller Bbm