Kiley is noted for combining classical and modern styles in his landscape architecture. Kiley's noteworthy projects include the Gateway Arch in St. Louis, Missouri (with Eero Saarinen), the Ford Foundation and Lincoln Center in New York City, and the National Gallery of Art's East Building in Washington, D.C. (with I. M. Pei). He also worked on the John F. Kennedy Library in Boston, the Air Force Academy in Colorado, Rockefeller University in New York, Dulles International Airport in Sterling, Virginia, La Défense in Paris, and the Fountain Place in Dallas.