From expansive windows to intentional disorder in design, the $15M museum wing flatters and inspires

He paneled the new Louis Vuitton boutique at 57th Street and Fifth Avenue with luminescent screens, and perched suitcases on high, see- through shelves so the luggage seemed to hover in weightless glamour. For a Chanel office tower under construction in Tokyo, he magnified the texture of the designer's famous tweed to worshipful proportions, rendering its nubby black-and-white patterns in masonry and light.

That flair for flattering beautiful objects should serve Marino nicely in the elegant addition to the Nassau County Museum of Art, which unveiled the new $15-million wing yesterday. Part of his mission is to persuade would-be donors that their treasures would be as well-tended on this verdant Gold Coast estate as they would be at the Guggenheim or the Met. And soothing the wealthy is something Marino does very well.

These days, museums often turn to globe-trotting architects to boost their institutional sex appeal, and frequently wind up with quarters that upstage their collections. But Marino, who created an ersatz patch of Manhattan in Manhasset at the Americana mall, knows that good architecture can be self-effacing. For the Nassau museum, he is proposing a new building that graciously deflects attention both to its contents and to the original mansion, designed by Ogden Codman for the Frick family in 1900.

It begins with a long brick box. With his instinct for aristocratic pretensions, Marino saw that the ideal complement to Codman's English- style cottage would be a glass conservatory behind a high garden wall, like the one he had photographed on a trip to Sussex. He liked the combination of transparency and defense: angled panes of glass poking above a brick barrier, the better to cultivate orchids in splendor, warmth and peace.

Marino made his enclosure long and narrow, with large windows at either end to draw visitors through the galleries toward the views of greenery or snow. This is a shade-garden of art, a corridor floored with wood, bordered in stone and terminating in a luminous double-height gallery with one 28-foot-high wall framed in windows on three sides, for truly enormous works.

Atop this opaque-walled shed are set four boxy galleries of different sizes, clad in baked white aluminum. These second-floor modules lie askew across the garden wall like children's blocks knocked out of alignment by a passing pet. The roofs, too, are rakish - each one has a different slant, with one corner and a ceiling edge snipped off and filled in with glass. The effect is calculatedly messy, like the meticulous disorder choreographed for a fashion shoot.

The addition's two levels seem to belong to different buildings: the upper one glares and juts every which way while the lower one sits, dense and bulky and horizontal. Downstairs is an artificially illuminated tunnel; upstairs fills with the cool light of an artist's studio, flowing in from the northwest.

The new addition would add 15,000 square feet, doubling the museum's exhibition space, allowing the old mansion to be filled by the existing collection and the new one to be split between temporary exhibits downstairs and hoped-for bequests above. Expanding the container and the collection at the same time will require some fancy footwork, but among the virtues of Marino's proposal is its open-endedness, which contrasts with the self-contained poise of Codman's cottage. The addition's brick walls, which end in a stone terrace ideal for cocktail parties, might eventually be extended and topped with another upper gallery or two, as donors' generosity permits.

Marino describes his design as "neither too hot nor too cold": a compromise between the picturesque Frick estate and the museum world's lust for big, splashy boxes in which to display art. The design's immediate goal is to attract money and bequests, rather than architectural attention. And the money will matter: A bare concept demands fine execution, and a million here or there could determine whether the end-result looks like a jerry-built jumble or an elegant vessel.