The AIA named Tod Williams Billie Tsien Architects the 2013 winner of the Architecture Firm Award, the highest honor the association bestows on a firm each year.

The architects, who are married, have been working together for more than 30 years. When Williams, FAIA, hired Tsien, AIA, in 1977, it was her first job; the pair formed a partnership in 1986. "Within a very short period of time, I realized she was the best thing I could ever have," Williams told ARCHITECT in a studio visit last year.

Williams and Tsien were responsible for one of the highest-profile—and most controversial—projects of the year: the Barnes Foundation, which moved its galleries from their original home in Merion, Penn., to Philadelphia's museum row. Williams and Tsien were chosen for the commission by a search committee spearheaded by Pritzker Architecture Prize executive director Martha Thorne. The commission did not come without strings attached: The museum's trustees had stipulated that the new galleries had to "replicate the scale, proportion, and configuration" of the old ones. In the face of harsh criticism, both public and private, the architects embraced the restrictions imposed by the commission and designed a building dubbed "absolutely wonderful" by Vanity Fair's Paul Goldberger, who also described Williams and Tsien as "architects of extraordinary subtlety."

The Barnes was not the only arts project that the firm completed this year. The Reva and David Logan Center for the Arts at the University of Chicago, the firm's first project in the Windy City, references the city's skyline as well as its setting on the Great Plains. In 2003, Tod Williams Billie Tsien Architects' celebrated design for the American Folk Art Museum, a highly textured and idiosyncratic building completed in 2001, was awarded an AIA Honor Award. (The nearby Museum of Modern Art acquired the Williams and Tsien–designed building last year, prompting fears that it may be razed.)

The firm won another AIA Honor Award in 2012 for its work in transforming the Lincoln Center's visitor entryway into the David Rubenstein Atrium, a project that Lincoln Center president Reynold Levy says "reflects a respect for the materials used throughout the center." And Williams and Tsien won accolades for their part in curating the Arsenale exhibition for "Common Ground" at the 2012 Venice Architecture Biennale.

"Their work carries with it a spiritual value which transcends pragmatic solutions," says Toshiko Mori, FAIA, in a recommendation letter for Williams and Tsien. "Their projects respond to multiple and complex needs of clients, yet their solutions are simple and elegant. Their firm’s work brings forth the ideals of Modernism, yet is moderated with a contemporary sensibility and intelligence which makes their work rich, tactile, and useful."

The firm has maintained its studio in Central Park since 1981. Despite their ambitious portfolio, Williams and Tsien say that they are not seeking larger projects, but instead want to maintain the studio's current size (about 30 employees) and familial culture.

"Architecture in any studio is a long life, and a long day, and a lot of work," Tsien said last July. "We recognize that and appreciate it."

Past recipients of the AIA's Architecture Firm Award have included Perkins+Will, Lake|Flato Architects, BNIM, and VJAA, who was last year's recipient. Tod Williams Billie Tsien Architects will be honored at the 2013 AIA National Convention in Denver next June.