Peter Eisenman's design for the University of Phoenix Stadium is modeled after the shape of a barrel cactus. Along the stadium facade, vertical glass slots alternate with reflective metal panels. A translucent "Bird-Air" fabric roof fills the interior space with light and air. Two 550-ton panels in the roof can be opened during mild weather.
The University of Phoenix Stadium has North America's first fully retractable natural grass playing field. The grass field rolls out of the stadium on a 18.9 million pound tray. The tray has a sophisticated irrigation system and holds a few inches of water to keep the grass moist. The field, with 94,000 square feet (over 2 acres) of natural grass, stays outside in the sun until game day. This allows the grass to get maximum sun and nourishment and also frees up the stadium floor for other events.