At first glance, Oslo, Norway’s efficient and attractive capital, suggests little of its 1,000-year history; its prim 19th-century buildings, stately public parks, and clean streets lend a sophisticated air. Though a walk through town is lovely in summer, some of Oslo’s best and most historic attractions lie behind doors. The city has an outsize number of museums, enough to satisfy a wide range of eccentric interests. At the FRAM Museum, board the strongest wooden ship ever built, used by Norwegian explorers to ply the Arctic and Antarctic. At the National Gallery, marvel at Norway’s largest public collection of art. Some of Oslo’s more obscure museums—devoted to glassworks, the playwright Ibsen, and children’s art—are worth a stop on a rainy day, if for nothing else to appreciate Norwegians’ knack for cataloging and organization.