The royal family would build ice cellars to store ice cut from the frozen ice of the moat and surrounding lakes during the winter.

Ice harvesting? Preparations for supplying ice to the palace in summer begin in winter. Every year after the beginning of winter, the cleaned moat is filled with clean river water. When thick ice forms in late winter, officers from the Water Resources Department of the Ministry of Industry will select the ice surface.

The ice cubes were cut into one-foot-five-inch squares and transported to the palace.

Storing ice? To harvest ice, you only need a large number of people, but it is not easy to store ice for a long time. Where should the harvested ice be stored?

To the southwest outside Longzong Gate, there are four semi-underground buildings running north to south, which are ice storage cellars.

The underground part of the ice cellar is about 1.5 meters deep, and the wall is 2 meters thick. The ground is paved with large strips of stone, and the four walls are laid from top to bottom. The strips of stone are laid first, and then the strips of bricks are laid.

Up to the top, stacked all the way to the top of the cellar, each ice cellar can store more than 5,000 pieces of ice.

Using ice? In the Qing Dynasty, "wooden refrigerators" cooled by natural ice appeared, and this wooden refrigerator had the functions of both a freezer and an air conditioner.

Expanded information about what it looked like: According to the "Huidian of the Qing Dynasty", there were only eighteen official cellars in Beijing at that time, divided into four places inside the Forbidden City, outside Desheng Gate, Jingshan West Gate and Zhengyang Gate.

Private ice cellars appeared during the Republic of China. They were almost all excavated earthen kangs, which were filled with ice and then buried with soil.

Today, there are only three remaining ice cellars in Beijing: an unknown number of ice cellars in the Forbidden City, two in Xuechi Hutong, and one in Gongjian Hutong, all of which are official cellars. There are no traces of private ice cellars.