Their work also reflects the aesthetic tastes championed by the foundation's namesake, Albert Barnes. Although he was among the first collectors to recognize the importance of modernist artists such as Matisse, Cezanne and Renoir, he was equally passionate about vernacular crafts, and insisted that high-art and homey objects be displayed side-by-side. Williams and Tsien similarly knit together cutting-edge spatial ideas and artisanal materials.
Yesterday's announcement came right on the Barnes's self-imposed deadline, despite the filing of fresh lawsuits last month aimed at stopping the move. After an five-month review of six of the world's top design firms, the Barnes board voted unanimously Saturday to hire Williams and Tsien, according to Aileen Kennedy Roberts, who chairs the building committee.
She said the board was swayed as much by the pair's willingness to carry out the court's unusual architectural instructions as by the grace, effectiveness, and stylistic innovation of their buildings, which include the American Folk Art Museum in New York, the Neurosciences Institute in La Jolla, Calif., and the Skirkanich Hall labs at the University of Pennsylvania.
Williams and Tsien were the only finalists to have completed a Philadelphia building, and it is easily among the city's best new designs. Their Barnes will have to nestle in among the other monumental buildings on the Parkway.
"All the architects on the short list were great, but for this particular project they were the right architects," Roberts said. "They're creative, and they understand complexity."
No timeline was given yesterday for completing the project. But the architects expect it will take about a year to finish a design for the $100 million museum and education building, which will be located on the site of the Youth Study Center, between 21st and 22d Streets.
Although none of the finalists was asked to submit drawings or models for the competition, it appears that Williams and Tsien won over the Barnes board by outlining a strategy for solving the vexing problem of building a museum within a museum, one that avoids making the galleries feel like period rooms embalmed inside a giant sarcophagus.
The concept, which will certainly require extensive study, would retain the current sequence of galleries - just as the court ordered - but blow out the spaces between the walls. Those new voids could then be turned into landscaped courtyards and gardens that connect the galleries with the natural world and allow some natural light to filter into the spaces.
Such an expanded sequence, Williams said, could also help make the Barnes' tiny rooms feel "less claustrophobic." Yet the foundation would still be able to install the paintings and decorative objects according to the theories prescribed by Albert Barnes. His Merion galleries integrate painting, craft, plantings and light into a single thrilling experience, and are as profound and original as anything hanging on the walls.
When Montgomery County Orphans' Court Judge Stanley Ott ruled in 2005 that the foundation could break Barnes' will and move the collection out of his Merion home, many architects were appalled by the idea of having to replicate the original galleries, designed in 1923 by Philadelphia's Paul Cret.
"We struggled mightily with this," Williams acknowledged, but ultimately came to accept that the eccentricities were what made the Barnes unique.
The new museum will be about three times the size of Barnes' home in Merion, with between 90,000 and 120,000 square feet. Barnes president Derek Gillman said he saw the move as an opportunity to carry out Albert Barnes' primary mission of educating the public about art.
Although Barnes envisioned the Merion galleries as a living classroom rather than a traditional art gallery, there are no actual classrooms. The new location will contain several such rooms. There also will be a gallery for special exhibitions that will feature borrowed works from other institutions. But foundation officials refuse to call the new building a museum and refer to it instead as a "Center for Arts Education."
The final short-list was almost evenly divided between practitioners of an exquisitely crafted modernism and more edgy theoreticians inspired by technology. Three of the finalists were winners of the prestigious Pritzker Prize.
Williams, 62, and Tsien, 57, whose firm is known as Tod Williams Billie Tsien Architects, were among the youngest of the group. They tend to work on just a handful of projects at a time, rather than parceling out their attention among many clients.
That devotion appealed to the board, said Roberts, who quoted Tsien as telling her, "This is the most important thing I'll do in my life, next to raising my son."
Gillman said Williams and Tsien "really do have dual element, an earthy aspect and a very refined and poetic aspect."
Their Skirkanich Hall, for example, presents an aggressively modern profile to 33d Street, but it confounds that stance by cladding the exterior in a hand-glazed brick the color of ginkgo leaves. Inside, its industrial-strength concrete walls were bush-hammered by hand to give them the texture of medieval stone.
The Barnes move has enormous implications for both the foundation and Philadelphia. While the foundation hopes to escape the financial problems that have plagued it for two decades, Philadelphia hopes to realize its dream of the Parkway as a real museum row. The Philadelphia Museum of Art begins its first major expansion with the opening Saturday of its Perelman annex.
Meanwhile, the Barnes's closest neighbor, the Free Library, is continuing to raise money for an expansion by Moshe Safdie. There are even murmurs that the terminally ill Calder Museum project might be resuscitated.
Coming up with an appropriate design for the Barnes "is a huge intellectual challenge," said Tsien. "But it's a great problem to have to solve."
Contact architecture critic Inga Saffron at 215-854-2213 or email@example.com.