(b Calvorde, nr. Magdeburg, 10 Dec. 1845; d Berlin, 1 Mar. 1929).
German art historian. His career was spent mainly in Berlin: he became director of the Gemäldegalerie there in 1890 and from 1905 until his retirement in 1920 was director general of all the royal museums of Prussia. Under his administration the Gemäldegalerie became one of the world's greatest collections. Apart from being a noted scholar, he was a pioneer of modern museum organization and display, combining pictures, sculptures, and frames in harmonious arrangements and achieving a balance between creating an up-to-date setting for works of art and reconstructing their historical milieu. His numerous publications were mainly on Italian Renaissance sculpture and 17th-century Dutch painting (particularly Rembrandt).