How did ancient Greeks and Romans keep food cool before modern refrigerators?

Before the advent of modern mechanical refrigeration, ancient Greeks and Romans primarily kept food cool by utilizing ice transported from mountains.1

To preserve this ice for extended periods, wealthy families constructed snow cellars—pits dug into the ground and insulated with materials such as wood and straw. By storing packed snow and ice in these insulated environments, they were able to maintain lower temperatures for months, providing a functional, albeit manual, method of food preservation.1