Architecture: A bold addition to a fine inheritance: The National Trust's visitor centre at Fountains Abbey in Yorkshire is a modern landmark, says Giles Worsley

FEW people would associate the National Trust with modern architecture. Great country houses, half-timbered barns, thatched cottages, yes; imaginative new building, no. So what was the trust up to when it employed Edward Cullinan Architects, one of the country's most innovative architectural practices, to spend pounds 2m - far more than it has spent on any other building - on a new visitor centre at its most popular site, Fountains Abbey in Yorkshire?

The abbey is not only one of the greatest and most romantic of English Cistercian ruins. What sets it apart are the contributions that successive centuries have made to it, architectural additions all of the highest standard. Fountains Hall is one of the finest surviving small Jacobean houses; John and William Aislabie's adjoining 18th-century landscape gardens of Studley Royal are of supreme importance and beauty; and William Burges's polychromatic church is a Victorian jewel.

The abbey and its surroundings, which attract more than 300,000 visitors a year, well deserve their listing as a World Heritage Site. But this exacerbated the trust's dilemma when it was forced to consider upgrading the car-parking and visitor facilities it had inherited from the local authority in 1983, and the decisions it took have not been without controversy.

The trust could have hidden the new building in a hole in the ground, or disguised it as a barn. But it decided to be bold. Each preceding century had produced its best for the abbey, and it would have been rank cowardice for the late 20th century to create a humble building.

So the trust commissioned from Edward Cullinan what it considered to be the best of contemporary design. Cullinan, who has little time for what he calls 'this frightened century', was enthusiastic about working in such a sensitive setting. 'If Aislabie could do it, so can we,' he argued. Since his Minster Lovell conference centre in Oxfordshire was finished in 1968, he has been known for designing modern buildings that fit intelligently into the countryside. He also has a particular sympathy with the North. He went to school in Yorkshire, at Ampleforth College, and now has a house in the remote Staffordshire village of Flash. He has a natural feel for the subtleties of the countryside and its vernacular architecture.

With its great, sweeping slate roofs and dry-stone walls, the visitor centre is very much a Yorkshire building, its open quadrangle a modern monastic cloister. It is also very much a Cullinan building. The sharp angles of the slate roofs, which cut into the sky, are offset by a gently curved lead roof on the inner face. The building - which includes shop, cafe, lecture hall and exhibition space - has a steel skeleton, clad with boards of cedar above dry-stone walls that seem to grow out of the earth. Such use of dry-stone walls may be unconventional, but they are cheap and environmentally sound, should last much longer than a mortared wall, require little maintenance and look good. Inside, functional, white-painted steel piers and curved beams contrast with the peacock colours of the ceilings, inspired by the choir of Burges's church. Visitor reaction should be fascinating. The traditional materials may well lessen any automatic suspicion of the new.

This may be one of those rare modern buildings that the public takes to its heart. But to treat the centre in isolation is to misunderstand its role and Cullinan's contribution. The approaches to Fountains Abbey used to be a mess - narrow country lanes clogged with traffic, ugly, exposed car parks and inadequate facilities in a long L-shaped valley.

The solution came with the purchase of Swanley Grange, the old monastic home farm that lies on a plateau above the valley. This opened up possibilities of access from the main road to the abbey and gardens (not all of which have been exploited because of objections by a syndicate with shooting rights to surrounding woodland).

Here, Cullinan was able to contribute to the landscape, drawing on his deep love and understanding of the principles behind the 18th-century garden. On leaving the main road, the access road immediately presents carefully controlled views of the spire of William Butterfield's church, and a sudden dramatic view of the 18th-century obelisk, previously hidden, thus whetting the appetite for what lies beyond.

On the approach to the visitor centre, Cullinan again plays visual tricks. The great abbey tower, framed across the axis of the building, appears to be dramatically foreshortened, but on moving through the building, the tower disappears from sight before reappearing in dramatic close-up as the path descends to the abbey.

For some, the idea that a visitor centre can be a significant building seems contrary. But the trust has done well to challenge such head-in-the-sand attitudes. It has had the sense to build well, neither scrimping on costs nor forcing the design to seek a commercial return.

Cullinan's building should be studied with care. One only hopes that the English Heritage and National Trust competition for the Stonehenge visitor centre - for which Cullinan, among others, has been shortlisted - proves to be as successful.

The author is the architecture editor of 'Country Life'.

(Photograph omitted)