It seems that there are caves in Shanxi, Shaanxi, Henan, Hebei, Inner Mongolia and Gansu, and some caves still exist and have become tourist attractions. That is to say, the loess layer on the Loess Plateau is very thick, some of which are tens of kilometers thick, so it is called green building to creatively use favorable terrain to dig holes and build cave buildings. In the past, a farmer worked hard all his life, and his basic wish was to build several caves. There is a cave, just like buying a house now, before getting married and starting a family. Men dig in the yellow soil, and women do housework and have children in caves. Some existing caves are very shabby, and some have been developed into scenic spots, which are relatively comfortable. The picture shows a dilapidated cave.