The Xi'an City Wall is the largest and best-preserved ancient city wall in China. It was first built during the Hongwu period of the Ming Dynasty (1370-1378), with a circumference of 13.74 kilometers, a height of 12 meters, and a width of 15 to 18 meters. The wall is constructed with blue bricks and is equipped with defense facilities such as watchtowers, arrow towers, and barbicans. The four main city gates (Yongning, Anyuan, Changle, and Anding) are grand and imposing. After more than 600 years of wind and rain, it still stands tall and is a historical landmark and symbol of the city of Xi'an. One can ride a bike or take a walk along it to experience the unique charm of the blend of ancient and modern.