2. Refrigeration (Fridge, Yakhchal)
The Persians invented early refrigeration methods in the form of a evaporative cooler, known as a Yakhchal, in 400 BCE. Upon invention, it was a dome-shaped object that was used as a means of refrigeration. Items stored inside would be kept cool within the subterranean part of the structure, with heat-resistant materials. This meant that items would remain cold throughout the year. The modern day equivalent is a refrigerator, which is an evolution of the Yakhchal.