Dhaka, Aug. 13 -- With temperatures nearing 40 degrees Celsius outside, Chicago native Michael Shedd visited a hotpot restaurant located inside a former air-raid shelter in southwest China's Chongqing Municipality.

In front of him was a bubbling, intensely spicy broth, but the heat and humidity did not seem to bother him.

"I feel it's cool as I get inside, just like there are air conditioners, but there are not. This is amazing," Shedd said.

Thousands of air-raid shelters were carved into Chongqing's mountainous terrain in the late 1930s and early 1940s. Once used as refuges for civilians during China's War of Resistance Against Japanese Aggression, many have since been converted into hotpot restaurants, teahouses and venues for Sichua...