Tianmen introduction: The rocks in Cishan are mainly composed of granite and mixed granite. Granite is hard and simple, with rich shapes. Under the influence of its joint development and weathering, it is easy to form majestic and magnificent pictographic objects with different shapes. Natural stone doors are one of them. There are five large and small Tianmen in Cishan, which are composed of Tiantianmen, Ertianmen, Nantianmen, Beitianmen and Tianmenyan (also known as Tianque).