Yakhchal: Ancient Refrigerators - EARTH ARCHITECTURE
By 400 BC, Persian engineers had mastered the technique of storing ice in the middle of summer in the desert. The ice was brought in during the winters from nearby mountains in bulk amounts, and stored in a Yakhchal, or ice-pit. These ancient refrigerators were used primarily to store ice for use in the summer, as well as for food storage, in the hot, dry desert climate of Iran. The ice was also used to chill treats for royalty during hot summer days and to make faloodeh, the traditional Persian frozen dessert.
I love classical practical physics. I keep filing these stories away for my eventual retirement place which I want (as of now) to be as off-the-grid as practical.