Driving along Beijing's fourth ring road, in the northern part of the city, a surreal bubble-like structure suddenly comes into view. It's a building like no other in Beijing, and probably the world. The city's National Aquatics Center, known as the Water Cube, will be an attraction for visitors to the city for decades to come, just to witness its strangeness.

The process that led to its creation began in July 2003, when Sydney-based architecture companies PTW Architects and Ove Arup, with the China State Construction and Engineering Corp. (CSCEC) and the CSCEC Shenzhen Design Institute won an international design competition to build the National Aquatics Center for the 2008 Beijing Olympics.

What they have created will ensure that the Water Cube, so named because of its shape and appearance, will be one of the most dramatic and exciting venues to feature sporting events during the Beijing Olympics in 2008 as well as one of the three centerpiece Olympic ventures.

John Pauline, a designer from PTW Architects and Chief Designer of the Water Cube, said that the seemingly improvised creation is the result of blending hi-tech with Eastern architectural beauty.

"In the process of designing, the question we discussed the most was how to absorb elements from Eastern architectual design in stadium construction and Chinese culture, especially when constructing a swimming stadium, which gave designers more room for creativity in outlook and function," Pauline said. He said their Chinese partners' emphasis on the traditional Chinese quadrangle courtyard shape had made an deep impression on him, and motivated him to try his hands at desiging a rectanglar building. "The final result is good."

The Arup/PTW design, playing on the geometry of water bubbles in a rectangular form, is specifically shaped to work in harmony with the elliptic main Olympic stadium, the National Stadium, designed by the Swiss architectural team of Herzog & de Meuron Architekten with the China Architecture Design and Research Group. The contrast between the buildings is also intended to reflect the ancient Chinese belief that heaven was circular and the earth was square.

In the early stages of design, PTW Architects reached an agreement with its Chinese partners that the main body of the National Aquatics Center should be transparent, which finally led to the proposal for the Water Cube.

"To arrive at the building's structural design, we reflected on all forms of water, including waves stirred by swimmers, to find an infinite image for this water theme," said Pauline.

During this process the designers settled on an image of soap bubbles. "All of the designers got excited when they found that soap bubbles arranged in an infinite array can give a random, organic appearance," said Pauline.

PTW's partner Ove Arup was given the task of generating a three-dimension model resembling soap bubbles, which became the steel frame of the Water Cube.

To bring the design to life, the individual bubbles were incorporated into membranes of ethylene-tetra-fluoro-ethylene (ETFE) and tailored like a sewing pattern. Entire sections were first pieced together and then put into place within the structure. The membrane was then inflated once it was in-situ and it will be continuously pumped thereafter.

It is the first time a membrane structure made from ETFE has been used in China. It is also the largest and most complicated membrane system in a single building project internationally. The feasibility of using ETFE came under attack during the design process but the designers insisted that it is strong encough to meet the demanding requirements of a swimming stadium.

"Although this is the first massive use of ETFE as a construction material in China, it is a mature technology abroad after being used for dozens of years. We decided on this material after a series of tests," said Toby Wong, another Chief Designer on the Water Cube, from PTW Architects.

Wang said the fluorin content in ETFE makes its chemical nature more stable than glass and in tests it has shown that it can survive a hailstorm. In the event of a fire the ETFE roof of the stadium can let open a crack to dispel smoke from the building. Wong said the designers had fully considered the impact of sandstorms in Beijing. He explained that the ETFE membrane surface is an impossible environment for mildew to survive on due to lack of water. The pillow cladding on the Water Cube is also dust-resistant. The life for the ETFE pillow cladding is 30 years and it can be replaced within hours.

While the construction of the landmark project officially started in December 2003, the membrane structure, with over 3,000 ETFE pillows, was completed in December 2006. The whole project looks set to be ready in October 2007.

Venue for all swimming, diving, synchronized swimming and water polo competitions for the 2008 Olympic Games, the arena, covering a floor space of 80,000 square meters, will hold 6,000 permanent seats and be installed with an additional 11,000 temporary seats during the Games. Spectators will witness 42 gold medals being won at the Water Cube.

The building's architecture has provided an opportunity to use new technologies in sustainable development. It uses solar energy to heat the pools and the interior area, and all backwash water and collected rain water will be filtered and recycled.

The erection of the building's steel constructure was highly complicated as it consists of 30,513 different shafts, which had to be pieced together according to a blueprint without a single mistake.

During the first stage of the unprecedented project, no more than 10 shafts per day could be jigsawed together due to lack of experience. Later, construction workers were able to install over 200 shafts per day. To maintain the high quality of the building, 180 welders working on the construction site had to go through 16 rounds of tests before getting the job.

To meet the latest sanitation standards of the International Swimming Federation, all the swimming pools in the Water Cube will use ozone as a disinfectant, which can effectively remove unpleasant smells in the pool while avoiding skin allergies. An automatic water level system has been adopted, which can save on disinfectant, power and refilled water by up to 50 percent.

Another water-saving technology used by the Water Cube is that filtered and sterilized waste water will be used to flush toilets, clean garage floors and water the grass outside the stadium. Another 4.5 tons of water will be saved using this technology each year.