Located in the south of the Beijing Olympic Green, the National Stadium (Bird's Nest) has a floor area of 258,000m2 and a site area of 204,000m2; and with about 80,000 fixed seats it is able to accommodate 91,000 audiences. The National Stadium, a special-grade oval building with designed service life up to 100 years, has a longitudinal length of 333 meters, a latitudinal width of 296 meters and a maximum height of 69 meters. The construction of the National Stadium was started on December 24, 2003 and completed on June 28, 2008.
The National Stadium is constructed on a plinth which rises gradually from the ground, so audiences can access the Stadium by walking along the plinth through the Olympic Green. In the north of the plinth is a sunken warm-up field, which is connected to the competition arena inside the main building by an athletes-only tunnel. The complex auxiliary buildings of the National Stadium and post-Olympics commercial facilities are arranged under the elevated ground to enable rational entry modes for different groups of people, as well as to maintain the clarity, consistency and integrity of the exterior of the main structure. Above the plinth are seven floors altogether, including service facilities for audiences, work areas for media and VIP reception areas; under the plinth are three floors in total, including zero-floor internal loops, parking lots and many functional rooms. The bowl-shaped stand consists of upper, middle and lower levels, and between the upper and middle levels are balconies with seats.
Among world's sport facilities, the National Stadium has one of the largest spans in its steel structure. Its roof maintenance structure is a steel structure covered by two layers of membranes: the upper layer is a transparent ETFE membrane fastened between the upper chords of the steel structure; the lower layer is a translucent PTFE acoustic suspended ceiling fastened under the lower cords of the steel structure and to the side walls of the inner loop.
The National Stadium was constructed with an advanced energy-saving design and such environment-friendly features as natural ventilation and lighting, full recycling of rainwater, utilization of renewable geothermal energy resources and application of solar photovoltaic power generation technologies. Under the football field of Bird's Nest are 312 GSHP (ground source heat pump) wells, which heat the Stadium in winters by absorbing thermal energy from the soil through embedded heat exchange pipes; and cool the place in summers by absorbing cold energy from the soil, saving considerable amount of electric power. The roof of Bird's Nest is equipped with a special rainwater recycling system, through which rainwater is collected for watering plants and grass, flushing toilets, fire fighting and even washing the tracks. These advanced environmental-friendly measures have turned the National Stadium into an enormous "green building" that lives up to its name.