BEIJING — Torch bearers carried the Olympic flame on the final relay of its long and sometimes contentious global tour Wednesday, greeted by rapturous crowds in the Chinese capital two days before it officially launches the Summer Games.

The arrival of the torch in the capital marks one of the concluding steps in China's seven years of preparations for the games that have cost billions of dollars, and one which Beijing hopes will serve as the country's symbolic debut as a modern world power.

The torch will tour Beijing before ending up at Friday's opening ceremony for the games. It will be carried by a diverse group, including China's first astronaut in space Yang Liwei, movie director Zhang Yimou and basketball superstar Yao Ming.

"I'm very happy to be here," said Yang before the relay kicked off from the Forbidden City, home of Chinese emperors since the 15th century.

"That the torch is finally in Beijing is a realization of a dream we've had for a hundred years," Yang said, minutes before he took up the flame as its first torchbearer.

Overseas, the torch relay was disrupted by protests or conducted under extremely heavy security since it left Greece on March 24, turning an event that should have built up excitement for the Games into something of a public relations disaster for the hosts.

The protests have mostly been in response to China's crackdown in March on anti-government riots in Tibet and to more general concerns over human rights issues in China.

The torch arrived back in the capital late Tuesday, after an emotional run in Sichuan province, the site of China's deadly May 12 earthquake which killed almost 70,000 people and left some 5 million homeless.

It was paraded Tuesday through about eight miles of the provincial capital of Chengdu. Hours later, a powerful aftershock struck other parts of Sichuan province in western China and nearby provinces, but it was not felt in Chengdu.

The original route of the torch in Chengdu was altered, taking it through an industrial part of the city rather than a more historic section that houses Tibetan communities, apparently out of concern that anti-government protests could mar the ceremony. Deadly riots against the Beijing government broke out in the capital of neighboring Tibet in March, and pro-Tibet activists have disrupted the torch relay overseas.

The Chengdu segment of the torch relay had originally been scheduled for mid-June but was postponed because of the massive May 12 quake, which killed almost 70,000 people and left some 5 million homeless. Chengdu was affected by the quake, but it did heavier damage to areas north of the city.