Weeks after opening a major expansion, Minneapolis’s Walker Art Center has accepted the resignation of its chief operating officer, who oversaw the year-long construction project. “[Ann] Bitter’s surprise departure comes at an awkward moment in the Walker’s development. Its addition by the Swiss firm Herzog & de Meuron has received rave reviews, but the building’s experimental architecture and mid-construction design changes forced the museum to cut costs by leaving the offices unfinished. Completing the offices and an adjacent sculpture garden are expected to cost up to $5 million more.”