The Dutch architect is known to be interested in the urban context of his buildings and many of his admirers were curious to see what he would come up with for a museum cut out of the side of one of Las Vegas' most spectacular fantasies, a hotel that has recreated what it calls "San Marco Square," along with canals with live gondoliers offering rides under an ersatz Bridge of Sighs.

Koolhaas made a pointed reference to the Las Vegas milieu by installing a canvas reproduction of the Sistine Chapel ceiling frescos on top of the Guggenheim Museum's glass and steel strutted ceiling. This bit of interior décor fits in with the overblown paintings that typically decorate the hotel, and the fact that Koolhaas borrowed from Rome rather than Venice is a fact that Venetian owner Sheldon Adelson and president Rob Goldstein were willing to overlook.

Otherwise, the museum is largely quarantined from its Las Vegas location. Once inside, the incessant sound of coins chunking in and clanking out of slot machines ebbs away and one is left with the exhibition at hand. Koolhaas designed a 63,700 square foot "big box" to house whatever the Guggenheim New York cares to send its way. A lime green stairwell descends to the lowest level and from there to the glass ceiling, the building measures some seven stories, rivaling the overwhelming entrance to London's Tate Modern.

In future, the space will doubtless be a perfect home to what Peter Schjeldahl terms "festival art," all those installations created for international biennials and in need of a secondary venue. But the "big box" is ill-suited to the Guggenheim's initial exhibition, "The Art of the Motorcycle," though that does seem to be the perfect sort of show for a Vegas audience.

The solution was to ask uber-architect Frank Gehry, who designed the installations at the Guggenheim Museums in New York and Bilbao, to perform his installational legerdemain once again. The result is a mad genius amalgamation of undulating ramps covered in shiny stainless steel, chainmesh curtains wittily tied back with swags, and projection screens with nonstop clips from famous motorcycle movies like The Wild One.

On the lower level, racing stripes of yellow, orange, blue and tangerine are airbrushed along the walls. Upstairs, Bilbaoesque tunnels with snowy plaster on the inside and stainless steel on the outside serve as voluptuous backdrops for 130 motorcycles of the last century, saving them from being completely lost in the enormity of the museum.

Vintage motorcycles have the edge in this show, from the pneumatic Harley Davidson and the tangerine Merken with fat whitewalls to the World War II-era BMW. BMW is also the principal sponsor. The enamel paint and chrome details of the bikes are enhanced by a fractious environment that generates the effects of speed, movement and light. Guggenheim Foundation director Thomas Krens, a well-known motorcycle enthusiast, arrived at the press preview with a posse of biker celebrities dubbed the Guggenheim Motorcycle Club -- Dennis Hopper, Jeremy Irons and Lauren Hutton.

Despite such toney support, I don't particularly think that motorcycles can be taken seriously as works of art -- even in our permissive era -- but they are fun to look at, especially in Las Vegas and in Gehry's installation.

Gehry's installation, however, is both the solution and the problem of the Guggenheim Las Vegas. There is so much Gehry to take in that one can barely make out Rem Koolhaas' building. Asked what he felt about having his old friend Gehry completely overwhelm his museum debut, Koolhaas replied with a thin smile, "It's a space that's designed to be overwhelmed."

Fortunately for Koolhaas, he had a second opportunity to make a first impression. The Guggenheim Hermitage Museum is what he calls the "jewelbox" (in contrast to the "big box") and appropriately enough, it opened with jewels from the collections of its namesake in St. Petersburg and from the Guggenheim collection in New York.

From the outside, this is signage as architecture. A wall of brown CorTen steel cuts along the front of the Venetian's faux terracotta surface, giant letters proclaiming "Guggenheim Hermitage." Inside the lobby, within 7,660 square feet, Koolhaas designed a museum both luxurious and modern. The interior walls are also made of CorTen steel but appear to be as soft as sienna velvet. They are suspended several inches from the floor, so that light seeps in from below, lending a flavor of airy Japonisme to the space, enhanced by the angled ceiling of blond wood. Narrow slot windows allow a diffused light to enter.

Without the Gehry installation, it is easier to see how skillful and restrained is Koolhaas' comprehension of space, proportion and surface. Speaking of surface, the masterpieces are attached to the walls with giant magnets, a fact as ingenious as it is quirky.

Krens, whose personal mission it is to establish worldwide franchises of the Guggenheim's prestigious collection, was particularly astute in establishing liaisons with the Hermitage Museum, an institution with vast holdings and a shortage of cash. A mind-boggling 35 million tourists visit Las Vegas each year. If a fraction is willing to spend $15 for a ticket, the Hermitage will be able to repair its leaky ceilings (the Gugg and the Hermitage pay rent to the casino for their spaces, and split the admission fees).

Once inside, there is no arguing with a show that quite accurately, for a change, is titled, "Masterpieces and Master Collectors." Among the 44 paintings, it includes Paul Cezanne's Still Life with Drapery and Henry Matisse's Still Life with Dance and Pablo Picasso's still life, Violin and Guitar. Not to mention Three Women, the painting owned by Gertrude Stein and singularly contributing to many other artists and collectors' understanding of Cubism.

These art history textbook plates could previously be experienced by traveling to Russia. For the next six months, you can see them in Las Vegas. What could be wrong with that?