Edith Rockefeller McCormick at "Villa Turicum" in Lake Forest, Illinois (1912, demolished). In 1907, he designed a townhouse for Sara Delano Roosevelt on East 65th Street in New York, now a historic landmark, the Sara Delano Roosevelt Memorial House. Eleanor Roosevelt called Platt "an architect of great taste" who with the townhouse had "made the most of every inch of space." The building currently houses the Roosevelt House Public Policy Institute at Hunter College. In 1912, he designed "The Causeway", Washington DC, a Neo-Georgian house in an extensive wooded landscape setting. He also designed a house in 1912 in Roslyn, New York for George R. Dyer. Platt also designed a large manor house and grounds, built in 1915 in the City of Little Falls, New York, (extant, in private ownership) for Mr. J. Judson Gilbert, owner of the Gilbert Knitting Company and several other then-prosperous factories in the Mohawk Valley region of Upstate New York. The MIT Endicott House in Dedham, Massachusetts, is another Platt-designed mansion built for H. Wendell Endicott in 1934, in use today as a conference center for Massachusetts Institute of Technology. Beginning in 1906, Platt had begun to receive numerous commissions from the estate of Vincent Astor. Platt turned to professional help in surveying large-scale projects from the sons of Frederick Law Olmsted. He also received detailed planting plans to fill his borders from Ellen Biddle Shipman, whom he had come to know through her gardening at Cornish, and whom he had instructed in presentation drawings by a draftsman from his own office, then sent to Grosse Pointe, Michigan to plant one of his designs. His more visible public commissions include the Italianate palazzo he designed for the Smithsonian Institution's Freer Gallery of Art (1918) in Washington, D.C. and the campuses of the University of Illinois Urbana-Champaign (1922 and 1927), Connecticut College, Deerfield Academy, and Phillips Academy Andover, where he designed the chapel and library and their settings. He fulfilled the University of Illinois's 1920s building program by designing 11 buildings, for many purposes, all in a Georgian style, with red brick, white wood and limestone trim, round and arched windows, and prominent gables, dormers, and chimneys. These included several buildings (1924–31) combining classrooms and offices, a dormitory, gymnasiums, plus such landmarks as the Main Library, McKinley Hospital, and the President's House. His Italian Renaissance-styled Russell A. Alger House, at 32 Lakeshore Drive, now serves as