The High Line has a long history dating back to the 1840s. (>>>View its complete history here). It is an elevated rail-road track running 22 blocks and is from an era when ships, trains, factories, and warehouses made the West Side of Manhattan America's premier working waterfront. In more recent years designers have been challenged to find potential for its unused industrial infrastructure.

In order to respond to such a transformation, along with multiple constraints posed by New York¹s enveloping zoning laws, addressing the adjacent Chelsea Arts District, while simultaneously remaining environmentally conscious, NMDA designed HL23. ³The prismatic nature of the geometry (which includes both planar/folded glazed surfaces and radially extruded surfaces of metal panels on the east), the material qualities, and the influence of the site all work together incrementally to build up a more complex experience,³ says Denari.

With one unit per floor and three distinct yet coherent facades, a custom non-spandrel curtain-wall on the south and north facades, and a 3D stainless steel panel facade on the east facing the High Line, HL23 contains 14 storeys and eleven residences - all with their own design.

There are nine full-floor apartments, a duplex penthouse with terraces, and a two-floor maisonette with a private garden at the building’s base. Residents enter the building from West 23rd Street through a lobby that is designed as a transition space from the street and the building’s expressive exterior.

The expected occupancy is late 2009, and upon completion HL23 is expected to receive a Leadership in Energy and Environmental Design (LEED) Gold Certification from the United States Green Building Council.