Although it looks like one structure, Museum Küppersmühle (MKM), in Duisburg, Germany, is a collage. This was the case long before its latest extension—which opened last week—was built. The MKM, which houses a collection focusing on post-war German art, was originally a series of three old flour mills on the banks of an inland harbor off the Rhine. These buildings, imposing but with plenty of charming brick detailing, including subtle classical pilasters and relief patterns, date from 1908. Several years later a new owner added a boiler house with a chimney. Adjoining steel silos were constructed in the 1930s.