Chongqing, China's largest megacity with more than 32 million residents, has shown remarkable progress in creating a sustainable urban future through digital technologies, offering valuable lessons for other megacities, a United Nations senior official said on Tuesday.

Anaclaudia Rossbach, UN undersecretary-general and executive director of the UN Human Settlements Programme, or UN-Habitat, spoke at the opening ceremony of the 2025 World Cities Day China Observance in the southwestern municipality. According to the UN, a megacity is typically defined as a very large city with a population exceeding 10 million people.

World Cities Day, observed annually on Oct 31, is the first international day dedicated to cities and the first such day initiated by China. Since 2014, both a global observance and a China-specific observance have been held annually. This year marks the first time China's observance is hosted by a city in the country's central and western area, which is less developed than its affluent eastern region.

"It is inspiring to see how the city has applied digital technologies to improve housing, governance, infrastructure and public services," Rossbach said during her video speech at the event. "This experience offers valuable lessons for megacities worldwide in advancing the Sustainable Development Goals and the New Urban Agenda."

The two-day event, themed "People-Centered Smart Cities Towards the Future", drew approximately 1,200 participants, including representatives from the UN, foreign diplomats, officials, experts, scholars and business leaders from home and abroad. It also features forums, exhibitions and field visits focusing on urban renewal, community governance, ecological restoration and industrial heritage protection.

Chongqing, a gateway to the country's vast inland regions and a major manufacturing hub, was designated China's fourth municipality in 1997, following Beijing, Shanghai and Tianjin. Covering an area of about 82,400 square kilometers, it is comparable to Austria and five times the size of Beijing.

In a voluntary local review released during the ceremony, Chongqing shared its experience over the past decade on using digital technologies for urban governance, public services, industrial transformation, green development and international exchanges.

"Over the past decade, we have transformed Chongqing from an outdated industrial base to a hub of intelligent manufacturing, and from an inland region to an open gateway," said Xu Jian, vice-mayor of Chongqing, at the event. "The city has taken on a fresh look with enhanced competitiveness and a growing reputation."

In 2023, Chongqing partnered with Chinese tech giant Alibaba to launch China's first large model for urban operations and governance, utilizing artificial intelligence to create a knowledge system, work system and innovation ecosystem for the city.