Introduction to the middle gate: Chaoyang Gate has a base length of 28.9 meters (28.6 meters at the top of the base), a depth of 25.8 meters (25.5 meters at the top of the base), and a height of 31.98 meters. The middle door is 8.5 meters wide and 7.2 meters high, and the side door is 3.75 meters wide and 5 meters high.