When the Walker Art Center, Minneapolis’s popular avant-garde museum, set out to design a major addition to its building, it wanted the architecture to reflect the center’s commitment to art that doesn’t necessarily fit the traditional mold, but didn’t want a building that would seem out of place in the Walker’s existing neighborhood, which includes idyllic parks, historic churches, and a massive sculpture garden. The new addition, designed by Swiss architects Jacques Herzog and Pierre de Meuron, opens next weekend, “the first in a string of high-profile projects among Minneapolis cultural heavyweights to be completed. The Guthrie Theater, the Minneapolis Institute of Art and Children’s Theater complex and a new downtown library with planetarium are all in progress on expansion or relocation efforts of their own.”