Mayor John O. Norquist, architect David Kahler and other local celebrities were on hand for the grand reopening of the expanded Milwaukee Art Museum Friday, but when the doors opened at noon, it was Santiago Calatrava's striking expansion and the artwork inside that were the real stars.

MAM employees were estimating that nearly 1,000 people bore the brunt of the less-than-cooperative weather to be among the first to enter the new building. About 2,000 museum members toured the expansion project last week at a special invite-only preview.

Some of the shivering crowd that lined up under the cloudy sky came from as far away as southern California and Canada to be part of an historic occasion in Milwaukee's art world.

Almost to a person, everyone who entered could be heard gasping in awe as they rounded the corner from the small entryway into the bright (even on a dreary day) space, which echoed the buzz.

"This is a monumental project," says museum director Russell Bowman, "encompassing an exceptional architectural and engineering masterpiece, dramatic new gallery space, expanded facilities and visitor amenities and elegant public gardens."

Light streams in through broad, angled windows in the outer walls and flits through the repeating structural ribs, creating a vibrant, welcoming space. The long, white marble floors and the perspective of the ribs repetitively advancing into the distance pull one forward.

Further light dips down through curvaceous ceiling apertures that hug the length of the inner walls, which close off the gallery spaces that run along the center of the long building.

Outside the galleries are the West Promenade, which looks out over the future site of the Dan Kiley-designed public garden, expected to be completed in October, and the East Promenade, which offers stunning views of Lake Michigan and a selection of works by Jacques Lipschitz, Henry Moore, Fernand Leger, Auguste Rodin and others from MAM's sculpture collection.

At one end is the unfinished Quadracci Pavilion -- also slated for September completion -- and at the other are the older art museum galleries, which have undergone a complete makeover. (Click here to read that story).

The new building has added tens of thousands of sq. ft. of gallery space to the museum. In addition to 12,000 sq. ft. of galleries in the Calatrava structure, areas in the older buildings that once housed the shop, the large East Entrance and the MAM eatery have been converted to art spaces. In all, there is now roughly 30 percent more gallery space than before.

One striking example is the intimate new gallery that holds "From Generation to Generation: Milton Rogovin Photographs" -- an exhibition of engrossing photographic triptychs that trace a series of Buffalo, NY families over the course of 20 years. This gallery was once a storage closet.

Two of the three new galleries are open. One hosts "Collecting for the Millennium," which shows off some of the museum's recently-acquired treasures in many media, including a lovely Cezanne large plate color lithograph of "The Bathers" (1896-'97) and German Expression Paula Modersohn-Becker's portrait, "Brother and Sister" (1906), which renders a pair of siblings with Modigliani-esque simplicity of form and an earthy Morandi-an palette.

Other gems in a show that is bubbling over with fine works are a large chiaroscuro canvas, "Christ Before the High Priest," by Matthias Stom(er), painted in 1633, and a large, engaging Andreas Gursky photograph, "San Francisco" (1998).

The largest gallery, however, is given over to an exhaustive exhibition of works by Sun Prairie-born artist Georgia O'Keeffe.

"O'Keeffe's O'Keeffe's: The Artist's Collection," curated by Barbara Buhler Lynes of the Georgia O'Keeffe Museum with MAM's own Russell Bowman, is the first to collect and show O'Keeffe's works from her own collection. It also seeks to explore how the management of her collection shaped the way in which we think about O'Keeffe and her works.