`A Victorian gem" is how Fionnuala Jay-O'Boyle describes Belfast. She should know. We are sitting in St Patrick's school, one gem which Jay-O'Boyle has helped restore to its finery. Built in 1828, the school was the first example of neoGothic architecture in the city. The erosion of time and a fire in 1995 reduced it to a shell.

However, what was once a burntout husk, is now a home for offices. To use a favourite Jay-O'Boyle phrase, it "is proof of the art of the possible". Jay-O'Boyle is chairwoman of the Belfast Buildings Preservation Trust, which was set up in 1996 as "a rescuer of last restore" which aims to rescue historic buildings and, in co-operation with local communities, give them new life and relevance.

"It starts very much on the basic premise that once you have lost these buildings you can't put them back," she says. A native of Derry, Jay-O'Boyle is proud of Belfast's architectural heritage: "It makes me slightly cross, sometimes more than slightly cross, that when people think of Ireland they think of Georgian Dublin - and rightly so. Dublin is a wonderful city. But what is less appreciated and less well known is that Belfast - with the possible exception of Manchester - is the finest Victorian city on these islands.

"There is a perception that Victorian isn't grand: it's about trade; it's about commerce; it's about working people. I think that's very sad. This is a city that is built on ship works, on steel, on rope, on sweat and toil. That is our city and it is a common inheritance. I think we should be confident about celebrating this city." She laments the buildings which have fallen prey to the Troubles and developers over recent years.

"We've lost buildings because of the Troubles but we have lost as many again through dereliction, neglect, decay and, quite frankly sometimes, indifference."

And indifferent is something that Jay-O'Boyle is not. "I think part of our modern mentality is if it's old it's no use. That's crazy. We are about sustainable development. We're about using what's there and that is an important message - particularly for this next generation who are about recycling, who are about being green, clean and environmentally friendly."

Jay-O'Boyle highlights the difficulties that Belfast faces in getting people to treasure their common heritage of bricks and mortar: "In terms of the city centre, I think there has been a problem. For good reasons and bad, people haven't been coming into Belfast. There has been no mixed-use. We haven't had our Temple Bar - though I'm not quite sure I want a Temple Bar. The centre of Belfast has not been anyone's priority for a long while. I think that is changing; I think people's perceptions are changing. "The work we do is as much about a battle for hearts and minds as it is about bricks and mortar. We've got to bring people with us. There is no point in lecturing or hectoring or demanding or adopting a morally authoritarian position. It's about proving to people that this can be done."

Currently, the trust is working on two main projects: restoring Christ Church (built in 1833) in Belfast's city centre and The Chapel of the Resurrection (built in 1869), the family and funereal chapel of the Donegall family who owned Belfast.

The Christ Church project has been undertaken with the support of the governors of Inst school in Belfast who own the shattered property. It is intended to make it into an information-technology centre which will serve not only the pupils but also the citizens of Belfast.

For Jay-O'Boyle, "buildings are something that cross barriers", and she believes people are beginning to think differently about them. She is delighted that the Conway Mill, an old linen mill on Belfast's Falls Road has been listed: "It is a wonderful, wonderful building and is very much part of our industrial heritage."

However, she is under no illusions about the difficulties still faced. Developers might listen and then again they might not: "I'm not saying we have converted them all. We have a long way to go. We have been business-like and professional in our approach. Developers and private sector can easily dismiss you as being a building charity. Yes, we have charitable status but we are recognised as being players."

Currently, Belfast has a number of designated conservation areas around St Anne's Cathedral, the Linen area (around City Hall) and the University Area. Harriet Devlin, an officer with the Ulster Architectural Heritage Society, aims to highlight, publicise and - if possible - stop the rot among buildings in the North in general.

Belfast city centre enjoys a degree of protective legislation and conservation areas which cover large areas of "special character". Some of the buildings within those areas are listed, and those which aren't listed are supposed to be protected. However, Devlin has found that there is "quite a strong erosion of character and demolition of buildings in conversation areas which we are very, very loath to see".

The society publishes an annual volume of buildings at risk. Volume number six was published this year and, Devlin feels, people's awareness of the importance of buildings is being raised: "There are more people aware that old buildings are of value but the developers are always out for opportunities. We would like to convince them that they should see old buildings as opportunities rather than a site. We have had some success in convincing them of some particular buildings. We have to keep pushing the message home that they have to think twice before knocking down old buildings."

She cites the recently renovated McCausland Hotel (home to the chef Eamon Cathain) on Belfast's Victoria Street as one example of how intelligent and imaginative use can be made of buildings. What was once a warehouse has been transformed into a luxury 60-bedroom hotel.

"There is a tremendous impetus to bring Belfast back into being a strong, economically vibrant city, but we have yet to convince people that you can do that but still keep heritage buildings, that people like to come to look at them and that they are an advantage with tourist potential," she argues.

She too is keen to dispel any thoughts that architectural heritage is the preserve of the middleclass. "The communities have to have some feeling of ownership of the buildings; otherwise there's not a lot of point," she says. Buildings must "have a distinct community focus" to change them from being simply inanimate walls to vibrant beings.