CHONGQING, Jan. 4 (Xinhua) -- Southwest China's Chongqing Municipality is famous for its incredible mountain views. However, it also boasts a less famous but equally impressive structural feature: large clusters of former air-raid shelters that are being transformed into bustling commercial venues, including hotpot restaurants, coffee shops, bars, bookstores and sci-fi exhibitions.

Chongqing was China's temporary capital during WWII, building a large number of air-raid shelters in which people sought refuge during bombing raids. There are over 16,000 former air-raid shelters in Chongqing, covering an area of around 1.1 million square meters.

In Chongqing's districts of Yubei and Jiangbei, 18 underground shelters have been combined into a tourism project called "Underground City," covering an area of 20,000 square meters.

In October, the project opened its first venue: Chongqing's biggest underground 24-hour hotpot restaurant, covering an area of 4,500 square meters and boasting 208 tables. The eatery has already attracted numerous customers since opening its doors.

Tai Xin, a 26-year-old woman working on the project, has always loved the city's cool, underground spaces. "In the past, people built this shelter for safety, and now people come here to enjoy this local delicacy. I think this kind of hotpot restaurant is meaningful as it reminds people to cherish a happy life," said Tai.

The original walls and structures of the shelter have been largely preserved, to maintain the link with the past. This minimalist approach has also helped to control renovation costs, according to Liang Huan, 40, who is in charge of the project's marketing.

"In the future, there will be places like museums, live-streaming bases, creative markets, coffee shops and other commercial venues in the 'Underground City,' reviving the mysterious air-raid shelters that were idle for years after the war," he said.

In Jiulongpo District, an underground bookstore that has been in operational for over two years has already become a cultural landmark among the city's bookworms. Built in a 45-meter-long air-raid shelter, the bookstore boasts over 15,000 second-hand books about Chongqing's history and hosts Chongqing-related lectures and salons, making the place a living record of history.

"The shelter is a very good place to open a bookshop. It's moisture-proof and is cool in the summer, which helps me control the costs of preserving the books," said Gou Jun, 56, the store owner.

Gou added that, for the people of Chongqing, the shelters are filled with many different memories, with the older generations associating them with survival.

When he was a child, Gou used to explore the abandoned shelters with a flashlight, like he was on a treasure hunt. Now, he hopes the young generation can find new meaning in these structures, in a more casual, relaxed and joyful way.

Chongqing began to develop this underground space in 2018, devising individual plans for each shelter and putting them to new use while documenting the local history. The air-raid shelters have witnessed various business formats, including hot pot restaurants, wine cellars, gas stations, parking lots, museums, bookstores, car washes and eateries, among others.

So far, these renovated shelters have attracted over 1 million tourists and provided jobs for over 100,000 people.