An adulterated residential fortress, the Osborne, which was built in 1883, was one of New York’s first major luxury apartment buildings and despite its somber appearance is palatial.

While the façades are a heavily rusticated combination of the Romanesque Revival and Italian Renaissance Palazzo styles in dark reddish brown stone, the lobby is a luminous Byzantine dream of gilded tiles with contributions by Augustus St. Gaudens, the great sculptor of the American Renaissance, muralist John La Farge, Tiffany Studios and French designer Jacob Adolphus Holzer. For those privileged to live or visit here, the romance of secret treasures is not fictional. No other apartment building can boast as sumptuous and dazzling lobby.

In 1889, Ware raised the roof to add servants quarters and seventeen years later a 25-foot-wing was added at its western end.

The building is often overshadowed in public awareness by the Dakota, further uptown on Central Park West, but the Osborne is more fascinating even if it is not as attractive on the exterior and its apartments are not quite as spectacular. What is intriguing about the Osborne is that, as a result of two major alterations in 1899 and 1906 its interior layouts are complex. The 1906 extension skillfully added more bedrooms to adjoining apartments. Most of the units have 15-foot-high ceilings facing 57th Street, but the rear of the building is split into many shorter levels and many of the large apartments have been subdivided over the...