Towers of power: Bienne's arteplage is the largest of the four and is based around a trio of monumental towers clad in a shimmering lightweight metal mesh skin.

Lying at the eastern end of the Bieler See, at the point where French-speaking west Switzerland meets the German-speaking north-east, Bienne is the largest town involved in Expo and has the largest arteplage.

Occupying a disused industrial lot on the edge of the lake, Bienne's arteplage explores notions of 'Power and Freedom'. 'Freedom' is loosely expressed through a deliberately chaotic ensemble of pavilions in the expopark of varying sizes, forms and materials, interspersed with more sober service buildings made of timber. Some of the pavilions are exquisitely designed for mere temporary structures -- 'Strangers in Paradise' by Ingrid Burgdorf and Barbara Burren (which takes an acerbic look at Swiss cultural stereotypes), has an immaculate concrete frame enclosed in a translucent skin of polycarbonate panels.

'Power' is in the hands of Austrian iconoclasts Coop Himmelb(l)au, who have created an assembly of towers and pavilions sheltered by an apparently hovering flat roof (actually supported by slim, angular pilotis).

Roof and towers are encased in a shimmering skin of lightweight metal mesh that softens and dematerializes their mass. At night, bathed in coloured light, they are transformed into huge, translucent, kaleidoscopic carcasses. The two parts of the arteplage are connected by a curved ramped bridge that arcs out over the lake to provide visitors with an agreeable and panoramic promenade.

Resembling broken chessmen or coffee pots, the trio of empty towers accommodate various bizarre functions. The most workaday one houses a staircase that connects with the curved bridge, but the intermediate tower is a 'kaleidophone' that senses and records surrounding noise (of water, visitors, the sky) and then mixes and transmits the resulting cacophony.

The third tower contains an assortment of Swiss national flags, some almost in tatters, gathered from buildings, back gardens and allotments around the country. (Donors were offered a brand new flag in exchange.) Like ancient feudal banners in a castle or the rotting cardinals' hats suspended in cathedrals, the limp flags have quiet dignity, reminders of the passage of time and the power of personal and national allegiance.

Architect

Coop Himmelb(I)au, Vienna

Associated architect

Gebert Liechti Schmid

Landscape architect

Zulauf Seippel Schweingruber

Photographs

Paul Raftery/VIEW