Capitalizing on the site constraint of a narrow foot print, the slender obelisk-like profile demarcates its existence boldly. It furthers its uniqueness by cladding clean white metal against the conventional stone of its neighbors. The new building is flanked by two existing mid-rise buildings. Air rights over an adjoining building permitted the tower to reach its full height. Zoning restrictions for the area attempt to maximize the amount of sunlight on the pedestrian level by requiring deeper and deeper setbacks as buildings increase in height. These regulations have been interpreted in a contemporary way in Cassa by introducing an inclined plane with a slope of 88 degrees on the north wall. The structural system consists of a flat plate and reinforced concrete columns with those on West 45th Street sloped to follow the zoning sky exposure plane.

The primary source of cooling in all hotel suites and condominium residences is water-source heat pumps. Separate HVAC units air condition amenity spaces. Prefabricated metal panels with integrated fixed and operable windows provide a fully insulated wall system built in sections spanning floor-to-floor.