Photo taken yesterday shows the inside view of China's National Indoor Stadium in Beijing, China. The National Indoor Stadium started operation yesterday to hold the "Good Luck Beijing" 2007 International Gymnastics Tournament.--Xinhua

The National Indoor Stadium, an important venue for the Beijing Olympic Games, unveiled itself for an Olympic test event -- the Beijing Gymnastics International Invitational, which started yesterday.

The stadium welcomed its first series of "Good Luck Beijing" events, namely artistic gymnastics, trampoline, handball and wheelchair basketball after going through check-and-accept just last week.

The National Indoor Stadium has a steel roof truss of double bowstring, boasting the biggest span of roof truss in the world.

It's just like a huge fan in the center of the "Olympic Green" and becomes a characteristic architecture along with the "Bird's Nest" and " Water Cube".

With the technology of steel scoria backfilling, natural lighting and solar generating, the contribution of the National Indoor Stadium shows its characteristics of "Green Olympics, People's Olympics and Hi-tech Olympics".

After being delivered, the National Indoor Stadium has a capacity of 20,000 which is expected to be the biggest in China.

From Nov. 28 to Jan. 25, four Olympic tests will be staged in the venue -- artistic gymnastics, trampoline, handball and wheelchair basketball, the events which will be housed here during2008 Beijing Olympic Games and Paralympics.

But not everything goes well in the first day's gymnastics qualifications, a glass lamp-chimney exploded accidentally near the media stand without causing any hurt. The working staff took immediate action to clean off the break-up pieces and carried through examination of all the lights.