In one of Manhattan’s noted landmark beaux-arts revival buildings, combine two untouched disparate penthouses (circa 1920) and create one cohesive seamless residence. Add, subtract and restore the unit to retain the best of the historic past, while still being appropriate to our time. Take full advantage of the four exposures of light, mezzanine, conservatory, rooftop access and views of Manhattan’s Central Park. (SheltonMindel)