Photo taken on May 15, 2008 shows the ceiling of the National Aquatics Center in Beijing, capital of China. The National Aquatics Center, nicknamed the "Water Cube", covered with more than 3,000 Ethylene Tetrafluoroethylene (ETFE) air cushions, is not only the first of its kind in China, but also the world's largest and most complex ETFE project. It was built in accordance with a water-saving design concept, a gigantic green architectural wonder.(Xinhua Photo)