The roof forms of ancient Chinese buildings vary widely, including veranda roof with five ridges, Xie mountain top with nine ridges, hanging mountain top with two ridges (noble ones are also made into five ridges) and hard mountain top, as well as Zan spire, ridge roof, helmet roof, etc. Among them, the peak of Xie mountain is the most beautiful roof shape.
Xieshengshan is also called Jiuji hall. As the name suggests, this form of roof has nine ridges, including the main ridge at the highest point, four vertical ridges on both sides of the roof, and four berm ridges at four corners. Xieshengshan is the roof level second only to the veranda roof. Because it has rich changes in positive ridge, vertical ridge, berm ridge and mountain surface decoration, it is also the most exquisite form of ancient roof, which is often used in Pavilion buildings.
Tiananmen Gate is the main gate of the Imperial Palace, and its tower, as a special pavilion, is a good choice in the form of double eaves and Xieshan.