Cool collection: hidden behind a fine traditional nineteenth-century facade in a chic shopping district of Paris, the design of a new shop is a coolly luminous expression of modernity.

Hidden behind a fine traditional nineteenth-century facade in a chic shopping district of Paris, the design of a new shop is a coolly luminous expression of modernity.

Calvin Klein is one of the most Europeanised of American fashion designers, typically selling uncluttered, simply designed clothing in fine materials and a few impeccable colours. Like his European counterpart Giorgio Armani - and to some extent like older fashion houses such as Yves St Laurent which once only sold exclusive couture - Klein sells mass market couture. Through his Collection stores, he also sells household goods; in other words, a lifestyle in which clothing can be coordinated with dining utensils.

Claudio Silvestrin has designed Klein's new Collection store in Paris. Spread over two floors of an early nineteenth-century building on the elegant Avenue Montaigne, the store sells clothes for men and women on the ground floor and things for the house - glass, china, bed- and table-linen - upstairs.

Fashion is an ephemeral business but still there is some correspondence between the enduring simplicity of Klein's designs and Silvestrin's austere inclinations. His elemental architecture of light and abstract form suggests infinity and timelessness amid western transience. The spaces he creates out of stone, opalescent glass and planes of soft light and shadow convey a sense of mystery and transcendence of the material world. This is irrespective of setting, as true of his design of a house set in idyllic Provencal landscape as of his remodelling of a London flat within a spec-built shell (AR January 1995).

The building in the Avenue Montaigne had once been a private residence and the ground and first floors were warrens of small rooms. The two levels were stripped out leaving only the structural columns, a new staircase was inserted and the fine stone face of the building restored. In general, it has to be said that the kind of craftsmanship the French apply to their cuisine is not carried over into building work and the finishing in places is rough.

The facade suggests the kind of chic couturier's boutique that has characterised Paris since time immemorial. Inside, instead of plush and gilt, is a luminous space, roughly rectangular and bounded by reflective white walls and clouded glass screens like curtains of light. These have been set across the windows as shields against the mundane, or are used as softly illuminated backcloths for the clothes. A limestone floor set in big flags flows towards the rear where on one side, on plan, the space steps inwards to form a tail neatly containing the changing rooms. On the other side, a service core cuts into the rectangle, with a storeroom behind a white wall curved at the corner.

Clothes are hung along the perimeters of the shop, and accessories contained in display counters with floating glass shelves set at intervals down their lengths and designed by Silvestrin either in steel or black stained wood. Their refinement echoes that of the exquisite geometric chair and table, chosen by Klein, and designed in the sixties by A. G. Fronzoni (with whom coincidentally Silvestrin has studied).

Usually in Silvestrin's work there is a moment, if not of frivolity, then of a deflection from the pure; and here it is contained in the design of the stone stairs to the upper floor which swerve away from the curving wall to leave an uneven ribbon of light around the edge of the treads. For a second you are reminded of the uneven broken treads in old stone towers. Upstairs, where the same vocabulary defines the space, the household objects include Silvestrin's oval limestone washbasin and bath. The pure monumentality of the latter object, seeming to transcend any fleeting domestic purpose, offers itself as a metaphor for the shop.