Answer: The bronze bingjian (ice container) from the Warring States era is considered the world’s earliest refrigerator. It consists of an outer square vessel (Fangjian) and an inner square jar (Fangzunfou), along with a matching bronze spoon. The bottom of the inner jar has three mortise holes that fit precisely with three bent hooks inside the outer vessel, ensuring a secure and stable nested structure. Wine was placed inside the inner jar, and ice was packed in the interstitial layer between the inner and outer vessels, keeping the wine chilled.

Image: Official Website of the National Museum of China