And now the greatest show of art - and artists - on earth as MoMA returns to Manhattan

It's being billed as the greatest gathering of artists ever staged, at what is arguably the greatest museum of modern art in the world - and every painter, sculptor, photographer or designer with work in its enormous collection is on the guest list.

It's being billed as the greatest gathering of artists ever staged, at what is arguably the greatest museum of modern art in the world - and every painter, sculptor, photographer or designer with work in its enormous collection is on the guest list.

For this week sees a series of spectacular parties heralding the grand reopening on Saturday of New York's Museum of Modern Art. After three years at its temporary space in the borough of Queens, MoMA is coming home to midtown Manhattan after a $700m (£380m) expansion programme that has spawned a huge and remarkable new wing designed by the Japanese architect Yoshio Taniguchi.

Those attending the first of the society soirées, on Tuesday, will be rubbing shoulders with probably the largest assortment of famous and almost-famous living artists ever to sip cocktails under one roof.

"Everyone is dying to see the museum and everyone will try to be there," gushed Karen Wright, editor of Modern Painters, who was flying to New York yesterday to be ready for Tuesday night. Look out for Cy Twombly, Jasper Johns, Robert Rauschenberg and, from Britain, maybe Damien Hirst and Rachel Whiteread.

"It will be the greatest gathering of artists ever staged," said one representative of the museum.

Or wait until Thursday, when MoMA will throw a second bash, but this time for the A-list of America's rich, famous, influential and notorious. Gazing all the way from the blue slate floor of the wide lobby up to the ceiling of Taniguchi's soaring 110ft atrium will be celebrities from both coasts. Playing music commissioned for the evening will be Sigur Rós, all the way from Iceland.

Neither evening is likely to provide the best conditions for viewing the reborn MoMA. The Independent on Sunday had the privilege of an early sneak visit on Friday, before 1,200 other journalists crowd in tomorrow. Workers were still scurrying, hanging pictures, affixing the last of the labels, testing the swing mechanisms on glass doors and even arranging the vases of white lilies in time for the parties.

But if they have the chance, the guests should take the time to move up through the new six-storey wing, built, at a cost of $425m, by Taniguchi, and visit the new galleries wrapped around the atrium, with their enormously high ceilings and expanses of white walls that seem to float on the floors. The architecture is not showy but rather discreet. Depending on your tastes, you might call its understatement sublime.

What the guests won't miss is the 1947 Bell helicopter suspended above the grand stairway leading up from the lobby, one of its rotors pointing the way to the galleries. "Our 'Winged Victory'" is how chief curator Terence Riley describes it, in a reference to one of the Louvre's greatest treasures.

They will probably also recognise many of those artworks that have formed the core of the MoMA collection for years - the Warhol soup cans, the mesmerising splattered canvases of Jackson Pollock, Monet's Water Lilies, Picasso's Les Demoiselles d'Avignon, Dali's Persistence of Memory and countless other landmark works.

Outside, visible through glass windows from the lobby, is the Abbey Aldrich Rockefeller Sculpture Garden, with more than 30 masterworks by the likes of Picasso, Rodin and Giacometti.

The galleries at MoMA now cover 125,000 square feet of space, up from 85,000 in the museum before the expansion started. It means it can put more of its enormous collection on show, and buy new pieces to expand that inventory. Some of those new acquisitions include works from young Britons. Gillian Wearing will not be at the party - her agent in London says she is "abroad" - but the Turner Prize-winner's photography will be enough to represent her. MoMA has purchased two Wearing pieces, a 20-minute video work as well as Self Portrait at 17 Years (pictured top left).

But the newcomers would do well to recognise what company they are keeping. It is exactly 75 years since the original opening of MoMA in November 1929. There were some pretty heady invitees on that day too - 35 Cézannes, 27 Van Goghs and 26 Gauguins among them.