Caisson Ceiling (Zaojing)
The Chinese name for the caisson ceiling, zaojing, means "aquatic plants" (zao) and "well" (jing). The two terms are relevant to water because there was constant worry about fire destroying the palace buildings. With water from the zaojing, the ancients believed the threat of fire would be averted.
It is usually in the form of a sunken coffer bordered in a square, a polygon or a circle, decorated with elaborately carved or painted designs. This architectural decoration has been found in Han Dynasty tombs which dates 2,000 years ago.