BEIJING — Beijing capped its six-week run as the center of world sports, ushering out the Paralympic Games on Wednesday with a lavish closing ceremony.

The ceremony marked the end of seven intensive years of preparations and $40 billion in spending on venues and infrastructure — all meant to symbolize China's emergence as a leading nation in the 21st century.

A 91,000 sellout crowd in the Bird's Nest National Stadium saw the ceremonial flame extinguished and the event formally handed over to London, which will host the next Olympics and Paralympics in 2012.

As with the Olympics, officials praised their Chinese hosts for the striking venues, tight organization and stadiums that were mostly filled for 11 days of competition.

The games were held in nearly perfect weather with blue skies and light traffic, leaving Beijing's chronic air pollution a distant memory.

However, traffic control measures are slated to end Saturday, with 2 million vehicles expected to return to the roads. In addition, heavy industry — shuttered for two months — and building construction is expected to return to pre-games levels, along with accompanying pollution.

"These games have been great games," said Philip Craven, president of the International Paralympic Committee. "Everybody realizes that. These are the greatest Paralympic Games ever."

The symbolic hand over came as London Mayor Boris Johnson and Beijing counterpart Guo Jinlong gathered on the infield. The London handover segment featured a red London double-decker bus, London landmarks like Nelson's Column and a moment when a "tea lady" arrived and the show stopped.

Because if one thing unites China and Britain, it is the agreement that all things — even an Olympic ceremony — must stop for tea.

China led the gold-medal table in the Olympics and did the same in the Paralympics, winning 89 gold and 211 overall. Britain was No. 2 with 42 gold and 102 overall. The United States was No. 3 with 36 and 99.

South African swimmer Natalie Du Toit, who also competed in the Olympics, won five gold medals. She lost her left leg after a 2001 motorcycle crash.

Compatriot Oscar Pistroius, a double-amputee sprinter who runs on carbon-fiber legs, won three golds in 100, 200 and 400 meters.

He is hoping to run against able-bodied athletes in next year's world championships in Berlin, and the London Games. Du Toit also plans to compete in the regular Olympics in London, in the 800-meter freestyle and the 10-kilometer open-water swim.

Four athletes were sent home for failing pre-competition doping tests — a German wheelchair basketballer, and powerlifters from Pakistan, Ukraine and Mali.

In a lunch Wednesday for foreign dignitaries, China president Hu Jintao said the Paralympics would push the government to improve care for the disabled, who historically have received little help or visibility in Chinese society.

"The Chinese government and people will build on the success of the Beijing Paralympic Games to carry forward the humanitarian spirit and advance in an all-round way the well-being of people with a disability in China," the state-run Xinhua news agency reported Hu saying.

Four thousand athletes from 147 regions and countries took part. That number is expected to reach 4,200 in Britain, which gave birth to the modern-day Paralympic Games. The genesis of the games came in 1948, when German neurologist Ludwig Guttman organized an athletic event in Buckinghamshire — northwest of central London — for soldiers wounded in World War II.

Unlike the tight security at the Olympics, security was much looser during the Paralympics, with the Olympic Green area filled nightly with people lingering on strolls between venues.

That area was often nearly empty during the Olympics, as ordinary citizens were not given access.

It also ends a special run for 100,000 games volunteers, who staffed every nook and cranny at the venues. Their friendly efforts were credited with softening the image of China's authoritarian government, which before and during the Olympics cracked down on security, visas and battled with journalists over blocked Internet access and freedom-of-the press issues.

"It's no use to be sad, it's all ending anyway," said Jiang Wei, a 19-year-old university student who worked since July 8 in the main press center. "We can take memories and get on with our lives."