Here's a message not all architects will want to hear.

Less is more. Even less money.

Exhibit A is the Parrish Art Museum, designed by Herzog & de Meuron, and scheduled to open on November 10. The museum, which is visible to anyone driving along the Montauk Highway on the South Fork of Long Island, New York, is a single low-slung rectangle, about 100 feet wide and more than 600 feet long, under a standing-seam metal roof.

It's not a small building, but it is a simple one. The design replaced an earlier scheme, also by Herzog & de Meuron, for a dozen linked pavilions, each with its own roof, suggesting the cottages and barns favored by Hamptons artists (from William Merritt Chase through Willem de Kooning and Chuck Close). But its outward modesty belied its internal complexity, and construction costs were estimated at about $82 million, according to Terrie Sultan, the museum's director. And then, when the financial crisis hit in 2008, it became clear that the Parrish, which has long occupied a 19th century building in the center of Southampton, couldn't raise that kind of money.

Sultan broke the news to Herzog & de Meuron and then sat down with Ascan Mergenthaler, the firm’s partner in charge of the project. When she told him that the budget had to be slashed, Mergenthaler picked up a piece of paper, and as Sultan tells the story, proceed to transform the cluster into one large volume. In the final design, the roof peaks twice, recalling a conjoined pair of long, low barns. A visit to the contractor's basement led Mergenthaler to choose raw, board-formed concrete for the long, north and south walls. The rest is steel and exposed lumber.

The new building cost about $26 million to build—70 percent below the previous budget. But is less less? When the new plan was announced, Nicolai Ouroussoff, writing in the Times, thought so, calling it "a major step down in architectural ambition."

Ouroussoff was wrong. True, no one can know what the "cluster of pavilions" would have looked like. I can only report that the rectangular building is a triumph. The materials are gorgeous. Those exterior walls, of board-formed concrete, with bits of the boards remaining on some of the panels, are stunning.

Inside, it’s one success after another. From a circulation spine that resembles the nave of a very elegant cathedral, roof beams rise to heights that make the galleries feel grand, but never grandiose. Most of those galleries have the kind of perfect proportions that create a sense of calm, and at the same time a feeling of exhilaration. And they are large enough for big works, including John Chamberlain sculptures, yet intimate enough to make even small, 19th century paintings feel cossetted. (Natural light promises to ensure that the paintings look good—better than at museums with millions of dollars worth of artificial lighting.)

Anyone who doubts that the $26-million Parrish is a major achievement need only wait until November 10. Then visit, and tell us what you think. And, while you're at it, tell us how you would feel if a client asked you to cut a project's budget by 70 percent.