Expat activities in the city.

Puebla and Wuxi signed a letter of intent for a sister city relationship in May 2013. Wuxi's cooperation with sister cities in Sweden, Denmark and Finland mainly focus on green energy, environmental protection and biotechnology.

Its sister cities in the United Kingdom, Japan and South Korea help Wuxi improve its governance, transportation and public services.

Prefectures, counties and towns in Wuxi, including Jiangyin, Yixing, Xishan, Huishan and Binhu, also started looking for their own sister cities from 20 years ago.

Culture and people-to-people contacts have been important aspects of such interactions from the birth of sister cities in the early 1950s in Europe, to promote reconciliation between former foes.

Tai chi, folk arts, education, tourism, film and other cultural industries are the most popular fields Wuxi exchanges with its sister cities.

According to Xu, Wuxi will look for more sister cities distinguished in innovation, ecological preservation and environmental protection in the future. "That's also what locals would like Wuxi to become," Xu said.

The China International Friendship Cities Association said 391 Chinese cities have formed ties with 1,900 sister cities in more than 130 countries and regions since 1973, when Tianjin signed China's first such agreement with Kobe, Japan.

The top three Chinese provinces with the most international sister cities - Jiangsu (268), Shandong (168) and Guangdong (144) - are also the three provinces with the largest economies.

The city of Wuxi and Germany's Leverkusen have different population sizes but their residents have much in common - especially the ability to share and the potential that comes from sharing, said Leverkusen's Lord Mayor Reinhard Buchhorn.

While Wuxi's population of more than 6 million dwarfs that of its European sister city, which is home to 160,000 residents, both are economic powerhouses along rivers - the Yangtze and Rhine respectively.

"With respect to the tasks and challenges of the future - for example, civic involvement, traffic policy and environmental protection - both cities have an equally big potential for innovation and will benefit from each other by their experiences," he said.

"Moreover, both cities are dependent on the qualification of excellent professionals, as a flourishing economy has its basis in the final analysis always on well-qualified people."

People-to-people exchanges have been a major pillar of the sister city relationship signed in 2005.

"Leverkusen and the surrounding region offer excellent possibilities for investment to entrepreneurs," Buchhorn said.

"Furthermore, this city partnership is very important for cultural and human understanding as well as the consolidation of the friendship between our peoples. It is a great honor to belong to the circle of sister cities of Wuxi. Personally, I admire at every visit the swift growth of this mega city and its great power in innovation."

The maturing relationship has been expanding beyond economics to also include culture, and Leverkusen is in particular seeking to expand educational exchanges.

"In Leverkusen you will find great interest in Chinese culture and the way of education," Buchhorn explained.

"The official sister city relationship enables both cities to get in contact now also on a civilian level, and to spread and intensify the contacts in the field of education. With this, the already existing good relations of our cities are put on an even more stable basis. By signing a treaty on educational topics, especially pupils and students of both cities will benefit from exchanges."

The city has established the Prince Taibo Classroom, where Chinese language is taught to the children of Chinese expatriates and interested German kids. The civil society organization Forum Wuxi-Leverkusen presents various aspects of Chinese culture during its New Moon Festival every September. The event brings together ordinary people, entrepreneurs and politicians, Buchhorn said.

Forum Wuxi-Leverkusen also organizes receptions every Chinese Spring Festival. The mayor added many couples wed at the Wuxi Pavilion, a garden pagoda sent to the German city as a gift in 2006.

"I personally hope very much that our both cities will further develop their close and friendly partnership and make it living," Buchhorn said.

"In a globalized world, with all its challenges and problems, it is important to learn from each other and to give support."