For more than 20 years, SOM was involved in the development of a master plan for the National Mall in Washington, D.C. In 1962, President John F. Kennedy appointed Nathaniel Owings as chair of the Pennsylvania Avenue redesign council, and the resulting 1966 Washington Mall Master Plan laid the framework for a dynamic, inviting, and pedestrian-friendly place. A second master plan developed in 1973, envisioned the construction of major cultural facilities, including the National Air and Space Museum, the Hirshhorn Museum and Sculpture Garden, and the National Gallery of Art Sculpture Garden.