Strolling through the Weisman Art Museum's expansive new galleries recently, director Lyndel King almost shimmied with excitement about the new skylights and floors, the Mississippi River views and the extra space that allows her, finally, to display more of the museum's treasured American paintings -- including masterpieces by Georgia O'Keeffe, Marsden Hartley and Minnesota's own Charles Biederman.

"I've been looking at this collection for a very long time, and it's never looked better," King said, alluding to her 30-year tenure as the Twin Cities' longest serving art museum director. "I think the paintings sing right off the walls. It just gives me goose bumps."

Rebranded as WAM, the jazzy metal-clad Weisman officially opens its $14 million addition Sunday after a yearlong closing. Designed by internationally known "starchitect" Frank Gehry of Los Angeles and Edwin Chan, a partner in the Gehry firm, the expansion is a seamless extension of the 1993 building that launched Gehry's career.

As his first American art museum, the Weisman became known as "Baby Bilbao" because it shows in embryo form many of the design features -- molten Cubism, light-filled interiors, a faceted metal skin -- that soon took spectacular shape in Gehry's best-known building, the Guggenheim Museum in Bilbao, Spain. Dubbed the "Bilbao effect," the cultural and economic sizzle generated by that project spawned an international museum-building boom as cities everywhere sought to revitalize their urban cores.

Architecture critics lavishly praised the Weisman, but the building was too small and tentative to make Bilbao-sized waves. It even appeared to have a split personality, half iconoclastic and half conventional. Its river facade glistened with folded-metal panels, but its campus side was a simple brick box. Inside, the skylights swooped and curved, but the galleries were traditional rectangles. Staff offices had curious shapes, but the public didn't see them.

The expanded Weisman changes all that.

Viewed from the outside it's a much more complex structure. The river facade is largely untouched, but on the north a new swooping metal canopy covers an expanded walkway leading to a pedestrian plaza at the museum's entrance. Big windows there offer glimpses into the new Target Studio for Creative Collaboration, a laboratory for guest artists and exchanges with other university departments.

On the east and south, brick-clad galleries on concrete pedestals pop out of the building's campus side like huge minimalist sculptures.

"It's great," said Tom Fisher, dean of the university's College of Design. The expansion "makes the original building much better. Now there are the same sculptural qualities on all sides, and internally it is more functional. It expresses movement much more than the original and it makes the building look complete."

Inside, modifications include opening a skylight that had been blocked by a wall, and reconfiguring boxy galleries into a vast central display area. Surrounding that are new, irregularly shaped bays for paintings, intimate nooks for furniture and light-sensitive drawings, and a sunlit ceramics gallery.

Team WAM

The Gehry firm is known for bringing its projects in on time and on budget, and the Weisman expansion was no exception. It helped that seven of the key players had also worked on the original 1993 building -- Gehry and Chan; King and three museum staffers, and John Cook, vice president at HGA Architects and Engineers, the Minneapolis firm that collaborated with Gehry's L.A. office. Cook also worked with Gehry on his first Minnesota project, a 1987 guest house for arts patrons Mike and Penny Winton.

New technology also expedited the project. Gehry is famous for using 3-D models, made from paper or cardboard, to give sculptural form to his buildings. He used models for both iterations of the Weisman. But turning models into bricks and metal still requires construction drawings, and that's where new technologies kicked in.

The original Weisman was the last of Gehry's "hand-drawn buildings," said Fisher. It has a blocky, Cubistic facade because 20 years ago, the architects drew flat patterns that contractors laid out like dress patterns, then cut and bent to wrap around the building's brick core. Now the architects use a computer program that Gehry's office adapted from one used to design airplanes. It allows for more curvaceous surfaces, such as the undulating canopy outside the new Target studio and the flag-like sheet now curling over the front door.

"Those forms that seem to be waving in the wind basically came from jet fighters, so the Weisman expansion is an essay in the shifting technology of building," Fisher explained.

The precision of the computer drawings also saved time, money and headaches by eliminating the need for expensive change orders or retrofitting.

"The drawings were fantastic, the best we've ever seen," said Brett Dunlap, project manager for J.E. Dunn Construction, which built the addition.

In Fisher's view, "Gehry's greatest impact is not on the form of his buildings but the processes he put in place to do the buildings. He wanted to do these very complex structures and had to invent the tools to make them. That has absolutely changed the construction industry. Contractors don't work from [paper] drawings anymore. They're just handed a disc and the whole building is essentially built electronically in the 3-D file."

Still, getting the new building up was no picnic. The museum's site is basically "an island surrounded by roads," said Cook. That dictated Gehry's decision to raise the new galleries on pedestals that jut over the street below. But the site is so small that there was almost no space for the construction firm to store equipment, unload materials or even place a trailer for the workers.

Furthermore, Washington Avenue SE., which zips past on the north, was torn up for construction of a light-rail line. Across Washington, another university building also was under construction -- the Science Teaching and Student Services building designed by the Kohn Pederson Fox firm of New York.

And every day, 20,000 students walk or bike past the Weisman's front door en route to nearby Coffman Memorial Union or classes on the university's West Bank campus.

"We had to build a lot of temporary walkways through our job site to keep the public safe and still allow construction, but we never once closed down the sidewalk," said Dunlap.

The 'Weisman effect' at the U

Embryonic though it was, the 1993 Weisman had a very positive impact on the university, Fisher said. Its presence made it easier, for example, to hire New Mexico architect Antoine Predock to do the McNamara Alumni Center in 2000, Steven Holl to design the architecture center in 2002 and Kohn Pederson Fox for the science teaching center in 2010.

"The Weisman was a statement that the University of Minnesota wants the best, leading-edge architecture the same way we want the best engineers, scientists and other scholars," said Fisher.

Reviews of WAM are still to come, but Fisher is confident that the expansion will bring new attention to the museum because it is rare for an addition to be designed by the original architect, especially one as famous as Gehry. This weekend the architect was expected to attend a Saturday-evening gala at the Weisman and to speak briefly Sunday at an invitation-only dedication of the Winton guest house. (After the Wintons sold the house in 2002, it was donated to the University of St. Thomas, which moved it to the university's Daniel C. Gainey Conference Center just south of Owatonna, Minn.)

"It's always interesting to see an artist reinterpret something he did earlier, and that doesn't happen very often," Fisher said.

And there may be a third go, because even the expanded Weisman isn't quite complete. It still has no cafe or dining facilities, although there are plans afoot for a coffee cart or snack bar to be added within a year. Gehry's office produced plans for a cafe that would have been cantilevered over the Mississippi, but it was shelved by budget constraints.

"We wanted to do it right, or not do it at all," said director King. "So we decided to do it next time."