What are the three wonders of the earth that combine three and seven into one?

Refers to the excellent construction technology in traditional Chinese architecture, which has the effects of heat preservation, sound insulation and fire prevention. The reason why the three wonders in one can play an important role in ancient Chinese architecture is that its structure is stable and has certain drainage functions. It can also effectively reduce the weight of the house and avoid foundation settlement caused by soft soil. Since ancient times, From an architectural perspective, by learning and applying the "three wonders in one" construction technology, not only can ancient buildings be protected and their service life extended, but it also has very important practical value.