The buildings comprising the United Nations Headquarters Campus are icons of International Style architecture. The Secretariat is a crucial landmark of curtain wall construction: arguably the first free-hanging curtain wall on a high-rise building in the United States.

The execution of the UN's Capital Master Plan brings the campus into compliance with 21st century requirements, while respecting the historic campus's Modernist origins. The replacement facades reference the original appearance, but also meet the latest sustainability and security requirements.

With a specialization in façade design, Heintges is the Architect of Record for all phases of the campus-wide façade project. The scope of this project involved analysis, documentation, and assessment of existing conditions; development of options for restoration versus replacement of glazed systems, restoration of marble and limestone clad facades, and design of historically sensitive new curtain walls.

The compromised condition of the original curtain walls, coupled with stringent security requirements, precluded repair or restoration, and pointed towards replacement. Our extensive experience in facade design and familiarity with the latest facade technologies allowed us to create remarkable facsimiles of the historical facades, while meeting project requirements.

One particularly innovative facet of the project was at the General Assembly's North façade, where vertical bands of solid and translucent materials alternate. Originally, a unique cast art glass was created by Corning to give the sense of translucent marble in the soaring lobby. This façade posed a particular challenge for the project team as the recipe for the existing glass had been lost. Heintges researched and worked with a glass fabricator to develop numerous sample iterations, culminating in an on-site visual mock-up. The final makeup of the high performance insulating glass incorporates etching and texture surface treatment, a two-pass ceramic frit, low-iron substrate, and lamination.