April is here, but inside Minneapolis's Walker Art Center it may as well be January. Los Angeles—based artist Catherine Opie has spent the last two winters documenting Minnesota's ice-fishing houses and the network of skyways that famously link the city's downtown buildings. Each photograph is accompanied by reflections from native Minnesotans on what it's like to live in the Star of the North (April 28—July 21). • Distilling Abstract Expressionism to a bare liturgical essence, Barnett Newman's paintings weren't really appreciated until the sixties, when the Minimalists came along. The Philadelphia Museum's comprehensive retrospective includes the 14-part series Stations of the Cross; the 26-foot-tall Broken Obelisk; and, of course, Newman's late near-monochrome canvases split by the vertical bands he called "zips" (through July 7). • "Through Afghan Eyes" takes viewers behind the headlines, with photographs and videos assembled at New York's Asia Society that depict daily life under Soviet occupation, from 1987 to 1992. Collectively, they make up a powerful visual history of a country's precipitous decline (through August 11).