The nine-story building is probably the tallest building in Mogao Grottoes. It is said that it is a building, and the inside is still carved on the stone wall of the mountain. The nine-story building is the part that can be visited by Class A and Class B tickets, and inside is a big Buddha with Wu Zetian as a prototype sculpture. But you can't take pictures inside, you can't stay too much, only the appearance photos are a memorial.