The first breads would have been cooked on flat stones heated directly in the fire. The bakestone remained the preferred method of cooking flat or unleavened breads in many cultures, from Mexico to Scotland, and is still in use. However, a natural step to take was to cover the bakestone with an inverted pot to contain the heat, and then to turn this makeshift arrangement into a domed, igloo-shaped or beehive, oven. A free-standing structure of this sort, with its own source of heat, merely replicates on a larger scale the principle of the stone and pot. Early examples have been found in Mesopotamia, Egypt, and the Balkans.