A complete interior renovation of this 3,300 square foot duplex apartment on Park Avenue involved the modernization of an unusually deep layout while preserving the traditional architectural style. A library/gallery opens through a mirrored muntined arch onto a fully glazed living room, suffusing the interior room with natural light. Interior walls and utilities were relocated to open up the kitchen and family room. Original moldings and other historic elements were recreated and modified to accommodate the new layout. Concealed storage, such as a built-in china pantry in the dining room, maximizes space efficiency.