The George W. Dunne Cook County Administration Building is a skyscraper at 69 West Washington Street in Chicago, Illinois. The building, constructed between the years 1962 and 1964, is 475 ft tall, and contains 35 floors. It has a concrete structure. The building, engineered by Fazlur Khan of the firm Skidmore, Owings & Merrill, is notable for innovating the tube-within-a-tube structural system.