Chastity in Vaduz: A reserved and very well controlled gallery makes a welcome contrast to the kitschy muddle of the rest of Vaduz, and offers calm spaces for contemplation.

Liechtenstein is a peculiar place. Sandwiched between Austria and Switzerland, the tiny state has had independence since the fourteenth century. Due to the benign government of the princes, who live in the Schloss that hovers over the capital Vaduz, its 30 000 inhabitants pay few taxes, and enjoy an income higher than almost any other people in Europe -- they approach the Swiss in affluence.

Few visitors would understand this from a casual visit to Vaduz, which seems at first like a dull Germanic provincial city. But suburban-looking houses often have a cow or goat in the back garden. As a town, Vaduz offers a concatenation of kitsch detailing scarcely emulated this side of Las Vegas (though wild ostentation is kept in check by burgerlich primness). But on each side of a vulgar villa are probably small but successful branches of a couple of international banks -- in fact, the villa may be one itself. With its liberal and secretive financial laws Liechtenstein is one of the world's great centres of shuffly money, and indeed, the monstrous former proprietor of this magazine, the vile swindler Robert Maxwell, had one of his last financial redoubts there.

In complete contrast to the kitschy muddle of the rest of Vaduz, the new national art gallery is calm, clear and precise. A carefully honed black rectangle huddles with the few obvious commercial buildings under the wooded slopes of the castle hill. Unlike its neighbours, it is not obviously welcoming. Its blank face, almost threatening, is adorned only with the chaste words 'KUNSTMUSEUM LIECHTENSTEIN'. But looking at it slightly from the side, the grimness becomes altered. Here is architecture, rather than sloppy sentimentality or crass commercialism.

The 400mm thick wall, cast in situ, seems almost geological; the day-work levels of its creation can be clearly seen like strata. There are no movement joints because the whole structure is prestressed. And the black cement and the carefully graded black basalt course aggregate are enlivened by green, red and white Rhine gravel, which makes the whole surface glitter and glint, changing as you walk round it. Carefully chosen, the basalt is smashed and sharp-edged, adding to the sparkle of the box. The whole exterior has been polished smooth to make the block more crystalline.

Inside, everything is equally apparently simple, but actually very carefully and sensitively thought about. The plan is almost diagrammatic. A welcoming cafe greets visitors, and a generous oak stair leads to the galleries above. Everything is calm, precise and minimal. Luminous ceilings are lit from the sky (on the top first floor) and balanced by artificial lighting; floors are oiled oak like the stairs, walls are of simple plaster painted white.

The architects clearly share preoccupations with their neighbour Peter Zumthor (over the border in Switzerland's Graubunden): light; materiality of construction, essence. And they are concerned with our response to the awesome business of making shelter, and inviting nature, which we reject by the very act of building, to influence our lives in the enclosures we make.

The building is the more remarkable because it has been made under a contract in which the builder had a great deal of say and the Swiss architects were distanced from its construction. Its design shows some of the virtues of Minimalism: you can keep the builder in order if you make the design simple and clear enough.