Beast of the Bay

Rarely has a building attracted quite so many similes. Some locals think it looks like a slug, or a bloated armadillo. Glimpsed from sea it seems very like a whale emerging from the deep. More generously, it's been seen as a castle - forbidding from the outside but with a line of glowingly festal lights just visible inside the carapace. For some it is already a white elephant - the latest example of a witless public-sector mentality.

The comparisons multiply because nobody knows what exactly Wales's all too multi-purpose Millennium Centre really is. The latest, and the last, of the big millennial lottery-funded projects opens next week - the legatee of more than a decade of wrangling about what should be built in the middle of the reconstructed Cardiff Bay.

Where once the docks exported coal and steel, the postwar rundown created a derelict landscape which has now been reclaimed by a toy-town marina, European-themed restaurants and apartment blocks.

The building of pastel-shaded versions of Alphaville in a post-industrial scene is a familiar tale. And so is the hope that a big arts building will be integral to an economic renaissance. It happened in Bilbao where Frank Gehry's beautiful slab of a modern art museum is now one of the world's wonders in a dreary dockland town. Michael Wilford's Lowry Arts Centre in Salford and Daniel Libeskind's Imperial War Museum North in Trafford Park attract the coaches across the north-west.

These are the buildings of the newish international style of public architecture - glitzy in aluminium or titanium, eclectic in their inspiration and undeniably monumental. These emblems have become icons. Millions have visited Bilbao's Guggenheim museum just to stand outside and gaze. Inside it's a pretty useless space for anything as mundane as a practically functioning art gallery. The walls are so huge that most paintings - other than some 60s pop art - would look like postage stamps.

But the point of such architecture is that it should also celebrate that other iconic element in our culture - the architect with a vision and a contract. No other profession is as adept at mingling commercial calculation with cultural cliche. Banalities about light and form, meditative space and interactive experiences between visitor and building coincide neatly with cost-benefit analysis. Those architects who followed their own inspiration, who struggled with patrons and created a reputation for "difficulty", such as Louis Kahn and Frank Lloyd Wright, are superseded by the smoothness of the IM Pei-Foster-Rogers model of success.

In architectural history that division of types starts with the complex, convoluted Borromini and the assured, worldly Bernini. But the branding of architects is a very contemporary development. If successful these millionaires run multinational companies which churn out the designs that win competitions. There is an in-house style that works even when the name at the top is not the one who executed the details.

Cardiff's Millennium Centre is unambiguously the work of Jonathan Adams of that very public-sector business the Percy Thomas Partnership, which seems to have built most of South Wales's council offices and hospitals for more than half a century. There is much in this building that places it in the contemporary monumental mode. This is the Beast of the Bay - a great big hulk wearing a tilted steel helmet as it glowers at its inconsequential neighbours. As a form it is an imposed solution, bearing no natural relationship with its local context.

At least the municipal Gothic of Britain's 19th century had a real life right in the centre of towns and, being the result of a commission by the city fathers, offered an engaged civic architecture. These contemporary studies in the grandiose, the result of a clever pitch to a quango, show instead the death of accountable local government.

But the details of the Millennium Centre's materials show another kind of political story at work. If this is not a convincing local-Cardiff building, it aspires to be a Welsh-national one. The use of steel, slate and timber on the externals represent Wales's industrial past and different regions. The enclosed nature of the centre is meant to recall the Wales of the Roman fortress and the Anglo-Norman castle. There's no glass and hi-techery at work here. Adams, in going all Welsh, has turned quite pre-modernist.

As an attempt at forging a vernacular style of Welsh architecture, this is quite a moment, even if the materials don't quite blend together. The symbolism is a shade heavy and offers an aesthetic version of that real Welsh tradition - the subcommittee covering all the angles.

But it is the belly of this beast which has to attract the audiences. For all the noise about international stature and a national style, this building can only work commercially if the South Wales coach parties decide that they like the beast on their doorstep. And, stranger things have happened. Remember King Kong and what happened to Fay.

· Hywel Williams's profile of the Wales Millennium Centre is broadcast on S4C on November 23 at 9pm and on S4C digital on November 28 at 10.50pm