TOYO ITO DOESN'T hate straight lines. The award-winning architect, who last year won the competition to design Taiwan's Taichung Opera House, due for completion in 2009, just prefers curved ones. 'I have liked curved lines since I was a child,' says the 65-year old. 'It's a bit like my character. When I talk, when I think - it's not in straight lines. It's a bit curved, it's soft. And in a way it resembles my inner character.' The plans and a large detailed model of the Taichung Opera House, on display as part of an exhibition in Tokyo to recognise Ito's achievements, show his affinity for complex, curved spaces. But he says the project's complexity grew out of simplicity. Just like Norman Foster's so-called Gherkin building in London, its exterior shape - rectangular pierced by large, curved shapes - reminds many people of something far more delicious: an extremely large chunk of cheese - a notion that Ito finds amusing, if misleading. 'When you look at a cheese, the holes are all compartments,' says the architect behind the Tod's building in Aoyama, Tokyo. 'They don't go through. But in this building, it's the opposite. All the holes go through, like in a cave. There's a continuity. And, if you think about the human body as well, from the mouth all the way down to the ass, there's a continuity. That's also a cave.' Such comments invoke the spirit of Tubism, a little-known movement that was forgotten almost as soon as it was launched in the 1980s. The Tubists, who included writer Takashi Hasegawa, poet Shuntaro Tanigawa, and literary critic Ai Maeda, saw their movement as the polar opposite of the geometrical analysis and dissection epitomised by Cubism. Rejecting the reduction of things to geometric forms, they instead tried to perceive them as tubular systems involved in a process. For example, whereas Cubism would reduce a tree to cylinders and cones, Tubism emphasised the tubular connections between roots, trunk, branches, and leaves. In the same way, an animal was best understood as a tubular digestive track, with other tubular systems for breathing and blood circulation. Initially intended as an aesthetic system, Tubism got little response from contemporary artists, but its appeal to a later system of architecture seeking to escape the de facto cubism of the modernist cityscape is obvious. 'I'm very aware of that movement,' Ito says. 'But in my case I'd prefer to put more emphasis on the tubes existing as part a network. I guess you could call me a Neo-Tubist.' The intestine analogy, beloved by Tubists and Neo-Tubists alike, has an additional appeal for Ito because a tubular model encourages gradation instead of abrupt changes and divisions. 'In the human intestines, there's an ambiguity between the inside and outside, and that inside/outside dichotomy is blurred and that's what I'm interested in.' This idea of blurring the borders between different functions and spaces has been essential to the success of the Taichung project, which seeks to serve as a place where interactions can occur between high art and popular art, artists and visitors, stages and auditoriums, and interior and exterior, with the contours of the building designed to blend in with the surrounding park. These same ideas were essential to Ito's breakthrough project, the Sendai Media-theque, completed in 2001. This was such an important design in his career that the present exhibition at the Tokyo Opera City Gallery marks it as a watershed by looking only at projects Ito has done since, presenting stylised models of seven key works on a large, white undulating floor - visitors have to take off their shoes to walk on it. Described as a 'multi-purpose public cultural centre,' the Sendai Mediatheque includes a library, art gallery, audio-visual library, film studio and cafe. 'With Sendai, we wanted to break up the idea of having confined rooms, where you do your reading and your research,' Ito says. 'Instead of providing secluded rooms, we provide places, and the self chooses whatever places he or she wishes. We also wanted different groups to share space. 'For example, old people might be in places where young people are, and therefore the old people look at the fashion of the young people and become more fashionable. Or mothers can look after their children and do other stuff as well because they're in the vicinity and can share the place. In that sense, giving places rather than rooms has become very meaningful for me.' Ito's philosophy of a seamless integrating architecture that brings together different groups and interests can sound idealistic, but it clearly sells well to public and private consortiums trying to create the broad-based political and financial support necessary for major projects. But the success of this architecture of unclear boundaries and overlapping functions relies on most of the users sharing similar societal values and having respect for each other. In more diverse or divided societies, would structures such as the Taichung Opera House or the Sendai Media-theque lead to confusion and even conflict? 'Sendai was possible because it was Sendai. If that building had been for another city, I would have planned it differently. But with the opera, it's a place where we hope to create the phenomenon of the temporary community, where people gather together for that moment and that community is created for that particular instant, and then dissolves when it's over.' This idea of a temporary community that then dissolves suggests that the Taichung Opera House, rather than being a giant piece of food, may, in true Tubist style, turn out to be more like an enormous digestive tract, continually processing Taiwan's cultural elite. Toyo Ito: The New 'Real' in Architecture, Tokyo Opera City Gallery, ends Dec 24; Sendai Mediatheque, Apr 13-May 19, 2007; Museum of Modern Art, Hayama, Jun 9-Sept 2, 2007