Introduction to Sichuan No. 1 Building: Along the Shuiguan Great Wall to the east, passing through the second and third gates, you can see a majestic watchtower. The steps under the watchtower are as high as 90 centimeters, with six holes and double floors. , the construction is clever. There is a horizontal plaque "Sichuan No. 1" 3-5 meters above the ground on the scroll hole. This watchtower is the starting point of the eastern part of the Great Wall along Badaling.