WORKac’s Stealth Building has been hailed as a model of sensitive but stridently contemporary historic preservation and adaptive reuse. A gut renovation and two-and-a-half-story penthouse addition to a building in a landmarked district, the project makes the most of a Landmarks Commission requirement that rooftop additions be invisible to passersby.

The exuberant roof form is a projection of sight lines from the street, leaving a volume crenelated to fit within the “shadow” cast by the building’s and its neighbors’ pediments and bulkheads. A secluded terrace is sunken behind the pediment, and the old elevator bulkhead houses a hot tub.

On the lower floors, four floor-through simplex apartments are organized around a kitchen/bathroom core that is conceived as an insertion with a sleeping loft and mini-greenhouse (watered by the master shower’s steam) on top. The restored 1857 cast-iron façade incorporates new column capitals designed in collaboration with artist Michael Hansmeyer, who developed a computer script to “grow” the floral elements of the Corinthian order fractally – a stealthy injection of contemporary design – and the first time the Landmarks Commission has approved a contemporary ornament on a historic building.