Long before modern refrigeration ancient Persians engineered ingenious ice pits in the heart of the scorching desert. Around 400 BC massive cone-shaped yakhchal reached heights of up to 60 feet and served as ancient freezers. Their secret lay in walls built from a special mortar combining sand clay egg whites lime goat hair and ash for superior insulation. In cold winters water from qanats froze overnight into ice that was harvested and stored with insulation to preserve food and refresh summer