In a country with 1.3 billion people, a visit to the World Expo probably endures more time, patience and physical strength than anywhere else.

It means one has to line up for security checks a full hour before the Expo Park opens at 9 a.m., in order to secure a reservation or a place in the front of the slow-moving queues that promise to grow endlessly outside some of the most popular pavilions.

All across the 5.28-sq-km enclosure in Shanghai's Pudong New District, crowds are seen everywhere: outside pavilions, inside souvenir shops, at snack bars and shuttle bus stops under the baking sun.

The Chinese are generally good at enduring long hours of waiting, an expertise they acquired at ticket counters and railway stations during their annual exodus for home before the Spring Festival.

The splendor of exotic culture and architecture on display at the Expo convinces everyone the waiting is worthwhile, even if they have to wait for four hours to access some of the most popular venues, including China's own pavilion and that of the United States, Spain, Britain, Switzerland, Denmark, Belgium, Japan and the Republic of Korea.

A complete visit to the Expo takes three to five days if one secures two most desirable destinations a day, and drop by the less crowded venues in between.

An Expo passport, sold for 30 yuan each, has found favor with the young people, who hold the passport and line up to get a stamp from every national pavilion they visit.

"We might not even be able to visit the China Pavilion this time. It's hard for us to get up early -- the child needs his sleep," said Xiao Jiutang, on the second day of a planned three-day Expo tour with his wife, two-year-old son and parents-in-law.

Xiao, a tourism manager from the southern Guangdong Province, also took the chance to study the feasibility for a new route combining the Expo Park and other popular destinations in and around Shanghai.

"It'd be a good choice for many as long as the cost is acceptable," he said. "I'll work out a package price at the end of this visit."

Window on the world

For millions of Chinese who find traveling abroad still a faraway dream, the Expo has brought the whole world to their doorsteps.

The Expo participants, on the other hand, are doing a good job to satiate the Chinese demand for exotic stuff and get across the cultural barriers.

The U.S. Pavilion has selected a team of 160 "student ambassadors" -- all Chinese-speaking students from American universities -- to provide assistance to the visitors and explain the essence of American value conveyed by the exhibits, including diversity, innovation and optimism.

The "ambassadors" promised to be "courteous, well-informed and respectful" and "smile often" when they swore in at an opening ceremony of the U.S. Pavilion Monday morning.

"It's gonna be stressful but happy," said Micah Phelps, a public relations major from Utah who is among the first group of 80 student ambassadors that will work at the Expo for three months.

Like all other "ambassadors", Phelps speaks fluent Chinese and knows a lot about China.

Phelps' parents worked in China in their younger days and his mother is the first Chinese language teacher in Utah. "My younger sister, who my parents adopted from China almost 10 years ago, is the only one who doesn't speak Chinese in my family."

The U.S. Pavilion shows films starring a number of Americans -- including Barack Obama and Kobe Bryant -- greeting the audience in Chinese and showcasing imagination and perseverance in preserving the earth and improving community.

"I enjoyed the films very much," said Jing Zefeng, 12. "I was particularly impressed by the American children's fantastic ideas, such as to fuel cars with fruit juice and travel wherever you want on the cloud... I had similar ideas when I was, say, about five years old."

Jing, a fifth-grader at a primary school in Shenzhen, a boom city in Guangdong Province, said the Expo was for him a window on the world. "I hope to meet more people and grow up to be a global citizen."

The U.S. Pavilion is receiving an average 25,000 visitors daily and except to draw a total of 6 million in six months, says Commissioner General Jose Villarreal.

"I had expected to see more high-tech stuff here," said Xiao Jiutang from Guangdong after touring the pavilion. "It's a little disappointing to see a display of sponsors. The American films are quite impressive, though."

Far from the American venue, on the southeastern end of the Expo park, the national pavilion of the Democratic People's Republic of Korea is another major attraction for the Chinese, who are eager to have a glimpse of its close neighbor and buy stamp albums commemorating the two country's traditional friendship.

The DPRK, which has attended an Expo for the first time, has taken "Paradise for the People" as the theme of its pavilion.

"It's unique but still similar to Chinese culture," said Zhang Weiguo, a 50-something visitor from the neighboring Zhejiang Province, who waited for at least 20 minutes to buy five albums. "The stamps with handshakes between former Chinese and DPRK leaders are good collections and make ideal gifts for friends and relatives back home."

A total of 204,000 people visited the Expo on Saturday, the opening day, and 221,800 visitors toured the park on Sunday, said Hong Hao, director-general of the Bureau of Shanghai World Expo Coordination.