C176 Etiology

Yun Xiuqing had seen cellars in modern times. People used to dig a big hole first, then make a roof out of lime, but in ancient times it was different. In ancient times, people dug a hole one meter in diameter, all the way down to a depth of a few meters, and then they started to dig even wider and wider. This was a great test of physical strength, endurance, and skill