BASEL, Switzerland (AP) _ Four years after the construction project was approved in a unique popular vote, one of the world's most important private collections of classic modern art has moved into a permanent home.

The new museum for the Beyeler Foundation, designed by Italian star architect Renzo Piano, houses the exquisite collection assembled during more than 40 years by Ernst Beyeler.

The idea took root after the collection gained wide acclaim when it was exhibited for the first time in Madrid in 1989. Beyeler, a leading figure in the international art market who also became one of his own best clients, credits his wife, Hildy, with initiating the museum project.

Planning had already begun for the construction (to be financed exclusively by Beyeler), when local critics forced a referendum, a move possible under the Swiss system of direct democracy. The vote favored the museum by a 3-to-2 ratio.

A similar proof of popular support for modern art had come from Basel burghers in 1967 when they voted overwhelmingly for a then $1.5 million to buy two Picassos. Beyeler had been a top campaigner for the purchase.

His longtime friendship with Picasso is stressed by 24 canvasses, works on paper and sculptures in the collection. Starting with ``Woman,'' dated 1907, when Picasso's ``Demoiselles d'Avignon'' became the herald of cubism, they cover six decades in the artist's work.

On view in the new museum are also about 140 other highlights of what Beyeler feels is ``proven'' modern art, ranging from an 1884 study by French pointillist Georges Seurat to a 1983 painting, ``Sand Dune,'' by Francis Bacon. The works include various Klees, Matisses, Kandinskys, Giacomettis, Dubuffets and other masters.

Paintings by Monet, Cezanne and Degas figure among works from the early modern art period. In a ``Monet room,'' visitors can admire the largest piece of the collection, one of his famous water lily paintings on a triptych 30-feet long.

A masterly ``Wheatfield With Cornflowers'' painted by Vincent van Gogh a few days before he killed himself in 1890 was added to the collection only this year.

American modern art is also strongly represented with works of Mark Tobey, Jackson Pollock, Roy Lichtenstein, Barnett Newman, Andy Warhol, Robert Rauschenberg and others.

Outstanding samples of tribal art from Africa, Oceania and Alaska, are equally part of the collection. They are placed throughout the museum, contrasting with the modern masterpieces.

This is in line with Beyeler's concept to make his museum a place of continuous exchange, a concept that also envisions two to three exhibits a year to ensure an interaction between modern classics in the Beyeler collection and present-day art.

The first of these special exhibits features 52 paintings and works on paper by Jasper Johns, who set the stage for the Pop and minimalist movements in American art. All are loans from the artist who, like Picasso, became an astute collector of his own works.

The works range from Johns' more than 10-foot-wide ``Between the Clock and the Bed'' _ inspired by Edvard Munch's self-portrait of the same title _ to a tiny ``Painting Bitten by a Man.''

Catalog author Robert Rosenblum writes that the anthology covering a period from the mid-1950s to the 1990s offers an entry into ``Johns's bell-jar world of self-exploration.'' The special show is slated to run until Feb. 15.

With an exhibit area totaling more than 29,000 square feet, the museum is situated in a sprawling park in the suburban community of Riehen.

Piano, whose many creations include Paris' Georges Pompidou Center, has designed a 120-yard-long landmark with solid walls clad with red porphyry (a type of rock with large crystals) imported from Argentina.

Light through the vast suspended glass roof, likened by Piano to a ``magic flying carpet,'' can be fully controlled. Thus, daylight is normally the exclusive source of lighting. At either end of the building, windows extending from floor to ceiling offer a picturesque view of the park.

Beyeler, 76, says a ``dream has come true'' for him with this ``symbiosis of art, architecture and nature.''

The $31.4 million museum was an ambitious undertaking for a man who once had to pay $4,500 for a Kandinksy in installments.

But it marked the beginning of a career that is unmatched, according to William Rubin, former director of painting and sculpture at the New York Museum of Modern Art.

``No other dealer has sold so many outstanding works by the modern masters to museums in Europe, the Americas, Asia, and Australia during the past 40 years,'' Rubin writes in the catalog prologue. He attributes Beyeler's success to ``the guts and commitment to 'bet large' on the greatness of 20th-century modernism some years before it was 'consecrated' by the art market.''

What made the dealer become a collector who refused many tempting offers for his pieces?

``There were always pictures that we just wanted to live with,'' Beyeler says. ``Even if I couldn't hang them and they just had to stand leaning against the wall, they were still there. And that was a good feeling. A much better feeling than having money in the bank.''