Bathing beauty.

Forssa is a little town in the south west of Finland which was founded as a centre for cotton spinning by James Finlayson, a British industrialist, in the middle of the last century. As in many other settlements of the Scandinavian industrial revolution, particularly in Sweden and southern Finland, Forssa has remained small, making remarkably little impact on the surrounding forests and lakes. It now has a more widely spread economic base than the company town it started life as.

Like everywhere else in Finland, Forssa has suffered of late from the detrimental effects of the economic setback of the implosion of the former USSR. But in 1988 its 20 000 inhabitants felt sufficiently prosperous to set up a company to build a swimming pool.

Swimming is one of Finland's favourite sports, but is out of the question in the open for much of the year, so a heated indoor municipal swimming pool can be much more than what such a pedestrian description implies in much of the rest of Europe. During the gloomy and frozen winter and in the cold spring and autumn such places, properly designed, become social centres (see for instance AR July 1993).

For a start, as well as the standard 25m exercise pool with its diving boards, there are lots of different varieties of water to splash about in: a wave place, a water slide, a children's pond, Whirlpool baths, a therapy and teaching pool, and for the really hearty, a cool water pool. As well as all these aquatic delights, the brief at Forssa includes saunas, a cafe, a solarium, gyms; disco and aerobic rooms and places for physical therapy. And there is a suite which citizens in less serious mood can hire to drink beer round an indoor barbecue and wander in and out of private saunas. The programme, based fundamentally on individual health and efficiency, but embracing many of the jollier aspects of social life, would be extraordinary in much larger towns, but to find it carried to execution by such a small community is a triumph and speaks much about the decency of Finnish life (and the wealth of the nation until recently).

Pekka Helin was asked to build the complex in 1988 and was faced by a rather nondescript, roughly square site in the suburbs, between an old quarter of villas and a new development of low slabs of flats to the south east. In the suburban setting, he decided to make an object building as a celebration of the civic effort, surrounded by lawns and tree-lined car parks.

All the aquatic parts of the building are in one big space: a huge double-height volume that could contain all the different pools (and the height of the highdiving board). Only a decade ago, this might perhaps have been a very Rational square box, but Decon has come to Finland, and has been interpreted, as usual in that country when it ingests an international movement, with a great deal of thought about the human consequences of the results. Helin has made the swimming hall into a square on plan which itself is divided into four lesser squares, the south westerly one of which is rotated by 20 degrees to the main mass. (It takes its cue from the angle of the neighbouring flats.) The rotation allows large areas of glass to be created in the roof between the concrete waffled slabs of the main roofs, so projecting daylight down into the middle of the big aquatic space.

A great, warm, comforting, luminous and exciting volume is generated. Almost all the pools are linked in a free-flowing geometry that allies the sensual curves of the Finnish shore-line with the rectilinear exigencies of the rules of competitive swimming. Little canals between bosky islands allow you to swim between one kind of experience and the other. The great slabs of the roof are carried on cylindrical in situ white painted concrete columns which are so thin and wittily placed that they seem almost invisible.

This spatial triumph is serviced and overlooked by a two-storey part of the complex again set at 20 degrees to the main square block. The glazed entrance and cafe are approached from the north-east corner.

A counter that moves from selling tickets to buns lines the long wall of the place. To the left is a long, largely top-lit corridor that gives access to the changing rooms, efficient transitional places between outer and inner worlds. Or you can turn off this corridor and go upstairs or by lift to the upper level of gyms, party suite and eventually out to the terrace, where a mobile bar can serve people who want to sit in the sunshine looking down into the great pool hall.

The terrace has another, external, stair so that it can become a bit of town, raised up and semi-autonomous from the main complex: a place in which to chat and snack on long summer nights, while vaguely noticing the more athletic members of the community disporting themselves below.

This stair is celebrated by a whoopy metal canopy that celebrates its presence (though it can do little to protect from rain). The gesture is echoed in ones of equal fun and drama which emphasise important moments in the inner life of the complex: the entrance, the diving board, the progression to the route to the interior through the changing rooms. All these are made plain by glass and metal interventions in the smooth white, mechanically rendered lightweight concrete walls that encase the noble volume.