Charles Adam Platt (1861-1933) was an American architect and landscape designer. Although best remembered today for his landscape and country house designs, he was also nationally known for his etchings, landscape paintings, commercial architecture, and institutional projects. He was largely self-taught in each of these disciplines, building his success on his ability to reconceive the classical tradition in architecture for the needs and desires of his wealthy, powerful clients. This collection contains materials related to Platt's personal and professional lives, the bulk originating from Platt's office in the form of project drawings, photographs, and records documenting architectural projects from 1901-1933.

The collection consists primarily of correspondence. The collection also includes contracts, invoices, inventories, appraisals, specifications, articles, photomechanical drawings and photographs.

This collection includes research papers, photographs, notes, and manuscript material compiled by Keith Morgan during his research on American architect Charles Adams Platt.

Included is Cox's correspondence, circa 1880 until his death in 1919, with architects, painters, sculptors, and writers including Bernard Berenson, Edwin Howland Blashfield, Will Hicock Low, John La Farge, Henry Oliver Walker, H. Siddons Mowbray, Theodore Robinson, Elliott Daingerfield, Lucia Fairchild Fuller, Howard Pyle, William A. Coffin, Russell Cowles, Daniel Chester French, Irving R. Wiles, James Monroe Hewlett, Harry Wilson Watrous, Edward R. Simmons, Maxfield and Stephen Parrish, Augustus Saint-Gaudens, Louis Saint-Gaudens, John C. Van Dyke, Wendell P. Garrison, Richard Watson Gilder, Robert Underwood Johnson, the architectural firm of McKim, Mead & White, Stanford White, Charles F. McKim, Cass Gilbert, Charles Adams Platt, and others. Of note are 136 from Cox to lawyer and author Leonard E. Opdyke. Correspondence, circa 1870-1922, with family members, particularly his father, Jacob Dolson Cox (a Union officer), his mother, Louise Howland King Cox (a painter), and his brother Jacob Dolson Cox, Jr. (a Cleveland industrialist and founder of the Cleveland Twist Drill Company). Correspondence of various other family members either among themselves, beginning circa 1860, or with Kenyon Cox is included. Also, manuscripts of Cox's essays, addresses, articles, and other writings on art, circa1870-1919; poetry; and juvenilia.

Also, a variety of professional and personal miscellany, such as correspondence, clippings, pamphlets, flyers, postcards, invitations, menus, receipts, a diploma, caricatures of colleagues, and Sawyer's monocle

This collection includes original and reprographic architectural drawings, black and white photographic prints, typescript specifications, and other papers relating to the architectural practice of Thomas W. Lamb, as well as his colleague and successor, John J. McNamara.

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.

The Woodlawn Cemetery archive documents the history of the grounds, mausolea, monuments, and operations of Woodlawn Cemetery, founded in 1863 in The Bronx, New York, and one of the largest in the United States. The collection includes architectural designs records, maps, photographs, correspondence, construction and maintenance records, and other historical documents, spanning 140 years of the cemetery's operations.