The Robert and Arlene Kogod Courtyard in the National Portrait Gallery in Washington, DC. From a plaque in the courtyard:
This courtyard, at 28,000 square feet, is one of Washington's largest indoor public spaces. First designed as an open-air courtyard, this area provided natural light and air to the surrounding galleries and offices.
In 2007, a steel and glass canopy of 864 panels designed by architect Norman Foster enclosed the space. Landscape architect Kathryn Gustafson designed the planters and water scrims. The Kogod Courtyard has been called one of the "new architectural wonders of the world."