Introduction to the first mountain gate: Historically, there were eight famous mountain gates in Yishan, and the first mountain gate was located in the south of Yishan. This mountain gate is called "Tiantian Gate", commonly known as "Youhe Gate". The original building is a brick and tile structure. It was built in the Yuan Dynasty and rebuilt in the Ming Dynasty. There are four characters written on the forehead of the door: "You are worthy of me".