Due to history and different geographic conditions, variations of decorative patterns exist between the architecture of the former imperial cities of Beijing and Hanoi, but many basic elements are similar, he adds.

For example, other than dragons and phoenixes, qilin (ky lan in Vietnamese), representing benevolence and auspiciousness, and the tortoise, representing longevity, also influence people's lives in both countries.

"Mutual learning among different cultures is like looking in a mirror, and we can thus better see our own," Peng says. "Joint archaeological research at Imperial Citadel of Thang Long will help us more vividly understand the history, and lay a foundation for the friendship of the two countries in the future."

Near the imperial citadel, Van Mieu, or the Temple of Literature, is where people worship Confucius.

After work, Wu often wanders among such temples and many other key historical monuments that resonate with his familiar places back in China.

Later this year, an exhibition on the influence of Confucianism across the world is to be staged in the Palace Museum. Also as an exhibition curator, Wu thus plans to loan some Confucian relics from Thang Long to better explain their spiritual legacies.

He stayed in Hanoi for Spring Festival in February. In his spare time, he also attends classes to learn Vietnamese. "Nowhere else gives me such strong feelings of emotional attachment," says Wu, who had worked for joint research in several other countries. "The traditional festive celebrations remind me of my hometown when I was a kid. When protecting historical sites, such intangible heritages also need to be cherished amid fast urbanization."