Persian engineers had mastered the technique of storing ice in summer

Persian engineers had mastered the technique of storing ice in summer

Persian  Yakhchāl 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 sometimes was used to store food as well. The subterranean space coupled with the thick heat-resistant construction material insulated the storage space year round. […]