"[2] He worked three times with Edward Clark, the wealthy owner of the Singer Sewing Machine Company and real estate developer: The Singer company's first tower in New York City, the Dakota Apartments, and its precursor, the Van Corlear.

[1] The following year, he was commissioned by Edward S. Clark, then head of the Singer Sewing Machine Company, to build a housing development.

As part of this work, he designed the pioneering Dakota Apartments[6] on Central Park West, novel in its location, very far north of the center of the city.

The two competing hotels were later joined together as the Waldorf-Astoria, which was demolished in 1929 for the construction of the Empire State Building.

Hardenbergh lived for some time in Bernardsville, New Jersey[7] where he designed the building for the school house built with funds donated by Frederic P.