Yakhchal
From Freepedia
A yakh-chāl is an ancient natural refrigerator.The subterranean domed structure often stored ice in it, but sometimes was known to keep food material in it as well.
Ice from nearby mountains was brought in during the cold seasons, and stored there for use later on during the summer months. This ice was from the ancient times used for the making of the traditional Persian ice cream.
The subterranean space coupled with the thick heat resistant constructing material kept the outside heat from reaching the interior space year round.
These stuctures were mainly built and used in Iran. Many remain standing that were built hundreds of years ago.
