This 92,000 ft2 (8,500 m2) expansion and 37,000 ft2 (3,400 m2) renovation to the Missouri Historical Society’s Museum is a three-level addition, connected to the original 1913 Beaux Arts Jefferson Memorial building by glass corridors and skywalks. Priorities in the design are energy conservation, integration of the designed system with the earth’s ecosystems, use of natural systems wherever possible, and use of natural light.