Building 101 is the Administration Building and focal point of the National Institute of Standards and Technology Gaithersburg campus, and its most predominant building in size, function, and location and a contributing resource within the NIST Gaithersburg National Register Historic District.  The lower floors comprise 233,500 interior gross square feet of this 345,785 gsf building that houses NIST’s primary public spaces including the library, conference center, auditoriums, instructional spaces, cafeteria, exhibits, and museum, as well as support, instructional and staff amenities. MAP developed a concept for a complete phased renovation of the lower levels and construction of a 50,000 gsf extension and prepared a document of technical performance requirements for a design-build contract. The renovations included modernized facilities, technology upgrades, tele-learning resources, and improved amenities. An important goal was improved building performance by replacing/upgrading the aging or obsolete engineering and communication systems, meeting current codes, and improving operations and energy efficiency – with phased implementation while the building operated.  Alternatives were explored, and the final document included a proposed design concept, performance requirements for all architecture and engineering disciplines, a space program and room requirements, a phasing plan for infrastructure replacements, and cost estimates.