This collection contains primarily project records, including drawings, files, specifications, correspondence, and photographs, related to the architectural practice of William & Geoffrey Platt. Projects including commercial, institutional, and residential buildings located in Colorado, Connecticut, Delaware, Florida, Louisiana, Massachusetts, Maine, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Virginia, Vermont, Washington, and France. The firm was involved in the design of many buildings and additions for institutions such as the Pierpoint Morgan Library, Princeton University, Smith College, and Deerfield Academy.