World's greatest art gallery

Taniguchi discreetly discloses its immensity through occasional openings that afford distant glimpses of staircases and galleries across the soaring atrium, while tinted windows provide storm-dark views of surrounding skyscrapers.

"You see layers of space, and views," Taniguchi explains, leading me to the fifth-floor landing and gesturing through the glass wall of the café to the city beyond. "What's especially important is to see the views of Manhattan. I wanted to give a special feeling to the visitor that they were looking at the paintings in New York, not in London or Berlin or Tokyo."

Unfortunately, the surrounding towers are a mediocre crop and the museum isn't tall enough to afford much of a panorama, so the "wow" factor that is so deliberately absent from the museum itself is also missing from the view.

Although beautifully crafted and expensively detailed, the main function of Taniguchi's architecture is to subordinate itself to the art, and it works: you soon forget it is there. "I don't give any strong sculptural quality," he says. "I tried to give a sequence of spaces so you don't get tired of looking at paintings."

And it is the paintings that, in the end, make MoMA worth every cent of the entrance fee.

Picasso's Les Demoiselles d'Avignon is here, with Van Gogh's The Starry Night, Monet's Reflections of Clouds on the Water-Lily Pond, Dalí's The Persistence of Memory (the one with the floppy clocks) and Warhol's Campbell's Soup Cans (all 32 of them). Plus dozens of other works of comparable weight and familiarity, all beautifully lit and generously hung in their capacious new home.

This is the complete story of modern art told through its greatest masterworks and MoMA simply doesn't need to resort to gimmicky architecture or quixotic hangs. Instead, as before, art is displayed as a series of isms organised in date order, starting around 1880 with post-impressionism and taking in cubism, surrealism, Dadaism and all the rest.

"As it's the only collection that can tell the whole story of modern art, there's an obligation to do just that," says John Elderfield, MoMA's calm and authoritative head curator of paintings and sculpture. "It seems to be a very big increase [in the admission price]," he adds, "but compared to going to Disneyland, it's nothing. And it's a private museum."

London's state-subsidised free galleries make for unfair comparison with an institute that relies entirely on ticket sales and the generosity of patrons for both its exhibits and its real estate. Elderfield admits that an important part of his job is identifying prospective purchases and then asking benefactors to pay for them.

But private - rather than state - patronage of the arts is embedded in the American psyche, and Elderfield's requests are often answered, as witnessed by the somewhat indiscreet silver letterings announcing "The Patricia and Gustavo Cisneros Gallery" and "The Donald B and Catherine C Marron Atrium", that are the only things besides the art allowed to sully Taniguchi's pristine walls.

The lavish giving of rich Americans is the reason why MoMA has the world's best collection, just as parsimonious state funding explains why Tate Modern has a second-rate one (and had to invent smoke-and-mirrors curatorial tactics to disguise the fact).

MoMA also makes London's obsession with the YBAs look parochial: there is no Tracey Emin, hardly any Damien Hirst and only a single Chris Ofili in the contemporary gallery. "It's part of our backing away from the vogue," says Elderfield, an expatriate Brit. "Maybe there will be something [by Hirst] in the future, when we may care deeply about him." Only works judged to be of lasting international importance are purchased. "The whole idea of national enclaves is terrible," he says.

Besides the incomparable painting and sculpture galleries at MoMA, there are also halls dedicated to architecture and design, drawings, photography and film and media, plus an expanded sculpture garden, as well as the obligatory restaurants, cafés and bookstores. No one seems to know the exact figure, but there are probably around 15,000 objects on display.

MoMA is not a place to pop in for a coffee and a quick cultural fix. It makes no efforts to be inclusive or controversial or to make art fun. This is a serious temple of high culture and it demands concentration, reverence and a whole day of your valuable time. Best to think of it as an investment.

The Museum of Modern Art, 11 West 53rd Street, New York (00 1 212 708 9400), reopens to the public on Saturday, www.moma.org Marcus Fairs is editor of icon magazine.