Beijing ? For the past seven years, through clouds of construction dust, thousands of meetings, millions of man-hours and an unprecedented political mobilization, China has waited for today.

At $43 billion, the Beijing Olympics, which begin today, represent one of the most expensive coming-out parties in history. And the belle of the ball has a lot to be proud of. China has risen from poverty and social chaos to engineer one of the most impressive economic success stories ever.

With a delegation of 600 athletes, China hopes to punctuate its success with a slew of gold medals between now and the end of the Games on Aug. 24.

“This is such a great moment for China,” said Chen Yongming, 55, an engineer and a big track and field, table tennis and swimming fan. “We’re very proud of our civilization.”

At a time when the government should be beaming, however, it has got the jitters.

An attack on a border police station in distant Xinjiang province Monday at the nation’s far western reaches killed 16 paramilitary members. The country has seen a wave of protests by foreign activists who managed to enter China despite stepped-up visa restrictions, a strict ticketing system and extensive screening.

On Thursday, China deported two Britons from Students for a Free Tibet who unfurled banners a day earlier near the Bird’s Nest stadium, according to a group spokesman, while roughly 2,000 Tibetan protesters in Nepal clashed with police while protesting Chinese rule of their homeland.

In response to a speech by President Bush in Bangkok urging Beijing to improve human rights, China’s Foreign Ministry called for bilateral dialogue. The ministry added in a statement: “We firmly oppose any words or acts that interfere in other countries’ internal affairs, using human rights and religion and other issues.”

In addition, the Turkistan Islamic Party, which has threatened to attack Olympic targets, again urged Muslims to stay away.

And pollution in Beijing remains a source of constant concern for the image-obsessed country, even on good days. Early today saw the city socked in under a heavy cloud of smog.

In some ways the lead-up almost has set aside the fact that representatives from around the world have gathered for a sporting event. About 10,700 athletes from 205 countries will be competing in 28 sports.

While some expect the early overhang of tension and heavy-handed security to fade once the games begin, the difficult lead-up has some observers wondering whether this party is worth the price.

In promising a perfect Olympics and pledging to keep protesters and even the weather under control, China has set itself up for disappointment and created a challenge for protesters.

“There’s been a drastic change in outlook by the political leadership from ‘Coming-out show’ to ‘Let’s let the Olympics pass without a crisis,'” said Cheng Li, senior fellow with the Brookings Institution in Washington. “They’ve really lowered expectations.”

International Olympic Committee President Jacques Rogge acknowledged this week that the Chinese face “some challenges.” But he remains at least publicly optimistic about the next 16 days.

“I think history will view the games as a significant milestone in China’s remarkable transformation,” Rogge said.