The Boijmans Van Beuningen Museum in Rotterdam is a complex amalgam of sections all built at different times. This new building makes the museum into a single entity again. Green-tinted glass sheets introduce a rhythm into the façade that looks austere and elegant, but its layering also gives a hint of the complexity of the building. Inside, there is a striking link between Adrianus Van der Steur’s 1935 brick building and the new one: old and new interlock without any brusque movements and turn the museum into a building that is both coherent and flexible.