āo(concave), in Chinese, refers to low place being surrounded by the high- rise buildings.
With the development of urbanization, the open spaces between tall buildings have become the āo, forming the specific area with the presence of high correspondence. Today's buildings are getting higher and higher, the ancient dream of living among the clouds has been realized, and we are farther and farther away from the land.
There were so many people living in the āo that was like a little utopia. They live in the area āo, not because of poverty, but to preserve the habit of human coexistence with the land.