Since 2004, BCA has been involved with the master plan for the United Nations complex. A noted example of the International Style, the complex was built between 1947 and 1953 and consists of four buildings: the General Assembly Building, the Conference Building, the Secretariat, and the Dag Hammarskjold Library.

As part of the plan, BCA created an extensive interior catalog of architectural finishes and features (e.g., walls, ceilings, and floor finishes; railings, stairs, and escalators; light fixtures; room dividers and fixed furniture; doors and door hardware, and wall-mounted clocks) to inform the restoration of the interiors of the General Assembly and Conference Buildings. Existing conditions were surveyed and documented using hand-held devices and photography. The data was then downloaded into a database to organize the information for preparation of construction documents.

BCA also wrote the preservation design guidelines for the interiors of the General Assembly and Conference Buildings to inform the restoration of the significant spaces of the complex. BCA designed conservation treatments for the interior finishes of these buildings based on the survey findings.

Most recently, BCA provided a pre-construction documentation survey of over 500 chairs and 250 tables in the Conference Building. This included creating an additional database of each individual item, including materials, finishes, and specific conditions of all fixed-in-place furnishings and wall dividers and modular architectural features in anticipation of the upcoming rehabilitation work at the building. BCA provided drawings, created by surveying instruments, showing the precise location of each item, as well as three photographic views of each item.