Scotland Preserv'd: celebrating Murray Grigor's musings on the decay of St Peter's Seminary

It was raining and the tide in the Venice Lagoon was high. Wellies were essential to take part in To Have And To Hold, Scotland's events at the 2010 Venice Architecture Biennale last weekend.

The water was rising outside the church of Santa Maria Ausiliatrice where an international group - including architects, academics and conservation specialists - gathered to watch Space And Light Revisited, Murray Grigor's split screen film about St Peter's Seminary in Cardross.

The A-listed building, designed by Isi Metzstein and Andy MacMillan of Gillepsie, Kidd and Coia, is an architectural masterpiece of its era. It opened in 1966 and has lain empty since 1984. It is now in a perilous state of decay. Partnerships between developers and its owners, the Archdiocese of Glasgow, and the vociferous attention of campaigners have failed to achieve a long-term solution.

To Have And To Hold was a series of public screenings, exhibition visits and a public debate, intended to explore current notions of conservation theory and practice. It took as its inspiration a new proposal for the site, the suggestion by Angus Farquhar's NVA organisation - the team behind outdoor events such as The Path and The Storr, and Glasgow's Hidden Gardens - that St Peter's might be stabilised as a ruin or "walk-through sculpture", integrated into its woodland setting, the site developed as a public landscape open for educational purposes and for incremental development.

"It's been a two-year dialogue with the diocese," Farquhar says. "Over the past 15 years or so, there have been many plans that have come and gone. Both the topography of the site and the recession seem to have put paid even to the best of these. The idea of superimposing a commercial solution on to the site seems to have been impossible. Our dream is to develop it as a public landscape and to be much more radical and innovative in the treatment of the site."

Grigor's 1972 film of the building shows St Peter's in all its glory: a building of stern modernism married with expressionist flamboyance, a place both of ancient processionals and everyday living. A second shot-by-shot follow up that Grigor made with cinematographer Seamus McGarvey in 2009 is a visceral shock, revealing a near-blasted shell of a building. But the impression of decay is constantly brought up short by the survival of the building's hulking personality and its bulky concrete skeleton, when nearly all its soft tissue of wood and glass has been stripped back.

The film might be seen to argue urgently for St Peter's complete restoration, but paradoxically it could also argue for a more nuanced approach.There has been considerable debate about why St Peter's never thrived long as a building, but there is one argument that it fell victim, not to architectural flaws or user dislike, but simply to a change of educational values in its patron the Catholic Church. It's common to think of St Peter's as a place for retreat, but its ultimate aim was to prepare young men for life outside its boundaries in the priesthood. In a sense the decay of the building has inadvertently opened up its closed world, and if NVA get their way, they would shift St Peter's gaze back outwards to the community to redevelop the sight for walking access and for teaching in the landscape.

What Scotland's presence in Venice seemed to suggest is that St Peter's is not part of a local story but part of a national and an international one about how we might honour and understand post war architecture, without either simply obliterating it as a failed social experiment or preserving it as an untouchable relic.

"We brought out our plans in the summer and are at the earliest stages of negotiation with the Diocese," Farquhar says. "St Peter's has clearly been a point of secular pilgrimage for artists and architects from around the world for the past 20 years. It has huge international currency. That currency, because it has accepted the state of ruination as a point of inspiration, is not the normal idea of preservation."

This year's Biennale is notable for wrestling with these issues. In the national pavilions the Netherlands examined its own post-manufacturing legacy of empty buildings. Belgium presented a room full of archaeological fragments, not the precious ruins of ancient cities, but the architectural details from public housing and station concourses. In the Italian Pavilion architect Rem Koolhaas's office OMA emphasised the "black hole" of demolition into which post-war developments across Europe are falling.

In highlighting NVA's proposals at Venice, the Scottish Government, Creative Scotland and the British Council have tapped into a wider debate about our attitudes to conservation of the post-war era and for the need to rethink attitudes to architecture during a period of economic transformation.

Where the new proposals may succeed, and where they need to be tested, is in the possibilities of opening out the story of St Peter's and the landscape that it is part of, into a wider public arena. The project's presence at the Biennale, Farquhar says, is "the end of the beginning, a stepping stone towards something real". And with that we step gingerly among the real stones of Venice, taking care not to get too wet.