The idea for The Snow Show, which takes place in Lapland this winter, crystallised half a world away, over lunch in a Manhattan restaurant. In the summer of 2000 Tuula Yrjölä, the Finnish consul for press and cultural affairs in New York, invited Lance Fung, a New York art curator, to visit Finland for the first time to witness the cultural activity in Lapland. Yrjölä, the project coordinator for The Snow Show, is a career diplomat and expert on Russia and Eastern Europe on leave from the Foreign Ministry until next summer.

"She mentioned the snow castle in Kemi," Fung recalls. Since 1996 LumiLinna - a snow castle containing an 18-bedroom hotel, an ecumenical snow chapel, an art gallery, a children's playground and a restaurant where the tables are made of ice and the seats covered with reindeer fur - has become an annual installation in Finland's industrial "red city" on the northern curve of the Gulf of Bothnia.

"I remember seeing a 30-second spot on TV all those years ago about the first Kemi snow castle," says Fung, chief curator of The Snow Show. "I was sitting on my mom's couch in Silicon Valley and called out to her about what those crazy Finns were doing. Was that it? Whatever, I initially thought I would get younger artists to do installations in the snow castle's bedrooms. But Tuula kept saying, 'You've got to go to Rovaniemi. There's an important art gallery there.'"

What was initially conceived as an art event has turned into a much larger cultural project, no longer just a collaboration between artists and architects, but one between two cities, involving participants from 27 different countries.

Fung started with a wish list of 500 artists, which was pared down to 30. Each artist has been partnered with an architect, several of whom were selected by Fung and his co-curators, Hilkka Liikkanen, director of the Rovaniemi art museum and Unto Käyhkö, director of the Kemi art museum, following a visit to NEXT, the 2002 Venice Biennale of architecture. The artists and architects are not being paid.

Among the artists participating are Yoko Ono (who is collaborating with Arata Isozaki), Anish Kapoor, Lawrence Weiner, Rachel Whiteread and Ireland's sole representative - the young London-based sculptor, Eva Rothschild, who has been paired with the Greek architects, Anamorphosis. Other architects taking part include Tadao Ando, Diller and Scofidio, Future Systems, Zaha Hadid, Morphosis, Enrique Norten, Studio Granda, Lebbeus Woods and Tod Williams and Billie Tsien.

"Lance "married" us, after he saw the work of Anamorphosis in Venice," says Nikos Georgiadis, describing his working relationship with Rothschild. "Anamorphosis, a Greek word used in Lacanian psychoanalysis, means "the return of form in an unexpected way - by itself - which rules out preconceptions" he says.

"I knew Eva's work; I had seen an exhibition of hers in a friend's gallery in Greece. We sat down together in London for six days in January and went very far, very fast. Our project relates to ancient labyrinths. Eva developed the idea of a mythical place with crystals or fractals - which can produce larger forms and yet cannot be deconstructed - and we worked on the idea of collectiveness.

"We want to respect the material as something that is animated and has a psyche, not as a material that you can build walls or bridges with. Snow is a material of luck. It costs nothing. It melts. It permits us to critique the narcissistic obsession with objects," he says.

Writing in The Snow Show, published in March 2005, Fung comments: "The idea to build a monumental amphitheatre excited me because it meant that the architects were using a form from their national heritage. Classical Greek architecture was designed for permanence but, in contrast, Anamorphosis built an iconic form that welcomed its accelerated reduction to an archaeological ruin in only six weeks. Rothschild gathered the remains of the other ice constructions and used them to pour, à la Smithson, a disruptive and prophetic line of rubble composed of ice crystals. The contrast between this line of rubble and the purity of the architectural form gave the work an immediate contemporary resonance."

The ambitious scale of The Snow Show has been pared back since last February's spectacular preview of Steven Holl and Jene Highstein's Oblong Voidspace (in Rovaniemi) and Asymptote and Osmo Rauhala's Absolute Zero: A Lighthouse of Temporality (in Kemi). The two preview pavilions will not now be reconstructed this winter.

The scale of the constructional undertaking in the two cities was initially underestimated. Other contributions which have been scratched for the same reason include those by Shigeru Ban, Foreign Office, Heikkinen and Komonen, Coop Himmelb(l)au, Greg Lynn, MVRDV, Snøhetta and UN Studio. Sensibly, ambition has been tempered by experience. Several of the 2004 installations will be conceptual, rather than spatial, hopefully proving easier to build during the tight, two-month construction period.

Half of the project's €3 million budget, partly financed through the European Union's structural funds, has been earmarked for building the structures that will melt within six weeks. UNESCO is contributing towards the project's educational component.

Fung describes himself as a "San Francisco city slicker" and seems a little surprised to admit: "Lapland brings a particular sense of moral or ethical responsibility. It was not 'Let's do a world's fair of snow,'" he insists. Nevertheless, The Snow Show will raise discussion about collaboration between art and architecture, has already furthered the study of snow and ice building and is bringing rare contemporary international critical attention to Lapland, a region in economic recession that has a population density of only 1.7 persons per square kilometre.

In 1944 when the Germans retreated, only twelve houses remained standing in Rovaniemi, Lapland's capital. Rebuilt to a plan by Alvar Aalto and situated where the mighty Kemi River meets the Ounasjoki River, the city of 35,000 inhabitants attracts half a million visitors annually - 380,000 of them from abroad - mostly to see the home of Santa Claus, who is resident 364 days a year (December 24 is the exception).

"Working with snow can easily degenerate into kitsch or become decorative," Fung says. "And you're dealing with a very risky building process - with a fugitive material that is changing every minute, one that's in flux. The challenge is how to control its wild nature and make something spiritual." The Snow Show rules are that each installation must comprise 80% ice or snow and be the result of an equal partnership between artist and architect. Each piece has a footprint of approximately 80sqm and a maximum height of 8m.

"Steven [Holl] and I have been friends for some time," says Highstein. "I have followed his work and I saw Kiasma as a shell. He attended my exhibitions. How did we work together? First I had to provide lunch and then he did. Mine was better. It was lunch and a drawing - that's how we worked. We thought there'd be run-off water as the structure melted, so we were considering channels, moats and pools. But it doesn't melt; the ice evaporates into the air.

"It all went smoothly until our first meeting, when we discovered the differences between architects and sculptors. I am interested in developing form and an approach to space, the classical sculptural problems. Steven is very practical. He wanted a concept. I made a drawing and Steven asked, 'What scale is this?' 'What do you mean?' I said. We had two different languages. He kept asking, 'What is it?' 'I don't care,' I said. 'I care about developing a form.'

"We talked about a theoretical form, a kind of vessel shape I've worked on for ten years or more. I made a template of the curve and said, 'This is the scale.' He said, 'What's the building block?' I was more interested in the curves involved. Steven concentrated on the transition of the material, its deterioration. For me, that's not so important. He's hoping a circular window will develop where we have made the ice thin, facing the city.

"The ice is polished by flaming it. The weather is helping; if it were colder, it would develop frost on its surface. It's a piece of architecture on the outside, more like sculpture on the inside, although the interior is not really a sculpture because it's never an object. There's a million things I'd change. I'd fine-tune the shape, which is too irregular - especially the junction of floor and wall - the curve is not pure. It took a monumental amount of labour to make this. It's all a series of compromises but nothing here is a disaster - although there nearly was one, when the city wanted a handrail installed on the steps."

Ice structures have a peculiar dynamism. The acoustic of the interior changes with the temperature. When it's cloudy the ice looks green; in sunshine it appears blue. Holl described Oblong Voidspace thus: "As an architect, I was asked what is my favourite construction material and I replied, 'Light.' This ice and light collaboration with Jene Highstein provided a test of the power of construction with "almost nothing". The only other material - frozen water - has no embodied energy, as it was naturally frozen and will be melted away to nothing by the time you read this text."

Lise Anne Couture and Hani Rashid of Asymptote and Osmo Rauhala did not know each other before Fung introduced them. Rauhala spent a month in New York, visiting Asymptote's office every second day. "Hani focussed on form," he says, "while I concentrated on content and how to show videos at minus 35 degrees - how to keep the lenses clean and deal with the heat of the projector."

"The recent history of the material is one of kitschy ice castles and carved swans," says Rashid, "but there's a great tradition of indigenous structures. Unless you use cubes or domes, you need to develop new methods and techniques - computer-generated moulds, laser measuring of curves. They'd never done that here before. It's a curious marriage of new technique and ancient materials. We're the guinea pigs, from both the curatorial point of view and in relation to the building process.

"Our approach has been the opposite of Steven Holl's. He is interested in the liquidity of the substance; we are looking forward to it being snowed upon. The safe approach is to say that snow wants to be in blocks, so let's build a cube. An igloo is made from carved blocks. Instead, we're dealing with packing and moulding a powder, a malleable material. We wanted an elusive scale. We wanted the snow to look as if it had been lifted out of the surface of the sea - like Ayer's Rock or Hans Hollein's aircraft carrier - instead of being made from blocks stacked on top of the frozen surface. The success is the doorway into the bigger dome; it's like an entry to a strange mystical place in Peru or Egypt. The dome is like an igloo or Santa Sophia or Brunelleschi. Osmo's skaters, filmed on artificial ice in Central Park, are like a fresco on the walls.

"With architecture, you theorise and do as much as you can on the drawing board before sending it out into the field, where it achieves permanence. But this is a living laboratory; we've been watching our project melt these last few days - during unexpected rain - before it was even finished. The ageing process is compressed. It doesn't occur to you as an architect to provoke a slippery material into constant evolution. We dreamt of a smooth surface but it gets pitted when the air is warm. We're trying now to get cleaner geometric lines, by using lasers instead of eyeballing, so that the controlled carving and moulding is not subjective. Otherwise it's just a mound. The only subjective bits should be the erosion of the surface due to nature - what nature wants this thing to be, in the Kahnian sense."

Markku Kotiranta built LumiLinna and Absolute Zero: A Lighthouse of Temporality, using artificial "cannon snow", made in early December and stored outdoors. More dense than the real thing, it has less air inside it but is not wet, and compacts under its own weight. Using an air mould, like a balloon, 1,000 cubic metres of snow was built up in layers, in a continuous process, before being carved to shape. New tools were invented in the process: expanded metal for carving and sandpaper for finishing. Seppo Mäkinen, an engineer and part-time teacher in the architecture department at the University of Oulu was the researcher when the Finnish "snow rules" - the structural design guidelines for building in snow and ice - were published in 2002. His company, Snowhow, is supervising the construction of The Snow Show.

"We took the ice for Oblong Voidspace from a lake, chosen for technical reasons - its proximity to the site and a road," says Mäkinen. "Nobody owns the ice, but you have to obtain permission from the landowner, from the fishing associations and from the hydro-energy authority."

Snowhow's crew placed a plywood template on the ice and, using long chainsaws, cut out the one-tonne building blocks - each measuring 50cm deep x 1m x 2m - which they lifted from the lake with a log-hand. They cut 60 blocks at a time, as many as could be laid in a day; it took three men two weeks to quarry the 500 cubic metres of ice needed for Oblong Voidspace.

"We transported the blocks at night - ten to a lorry - and built with them next day," says Mäkinen. "After laying each course we added water to the joints, using an air-pressure hose, to lock them together. Ice can be compared to brick in the way it is joined together, although it is a very fragile material," he says. Snow, on the other hand is "flexible, more like rubber than stone."

Links
The Snow Show: www.thesnowshow.net
The Snow Show, edited by Lance Fung, is published by Thames & Hudson, March 2005, price £14.95. www.thamesandhudson.com
The Morphic Excess of the Natural by Anamorphosis and Eva Rothschild: www.anamorphosis-architects.com/projects/snowshow/project_snowshow.html
Eva Rothschild: www.cmoa.org/international/the_exhibition/artist.asp?rothschild.

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