The Persian fridge
Persians may have been the first civilization to build and use "refrigerator buildings" to store ice and refrigerate food. Yakhchāl (yakh meaning "ice" and chāl meaning "pit") is an ancient type of evaporative cooler.
Above ground, the structure had a domed shape, but had a subterranean storage space. It was often used to store ice, but was also used to store food as well. The subterranean space coupled with the thick heat-resistant construction material insulated the storage space year round. These structures were mainly built and used in Persia.
By 400 BC, Persian engineers had mastered the technique of using yakhchāls to create ice in the winter and store it in the summer in the desert. In most yakhchāls, the ice is created by itself during the cold seasons of the year; the water is channeled from the qanat (Iranian aqueduct) to the yakhchāl and it freezes upon resting inside the structure. Usually a wall is also made along an east-west direction close to the yakhchāl and the water is channeled from the north side of the wall so that the shadow of the wall keeps the water cool to make it freeze more quickly. In some yakhchāls, ice is also brought in from nearby mountains for storage or to seed the icing process.