In 904 AD, after Han built and rebuilt Chang'an City, after the Song, Jin, Yuan and other periods, the expansion and reconstruction of the original Tang Chang'an City Emperor City in the Ming and Hongwu years, have been repaired many times since then, and many city gates have been opened after the founding of the People's Republic of China. [3][6] Xi'an City Wall existing 18 gates, respectively: Yongningmen, Zhuquemen, Domumen, Hanguangmen, Andingmen, Yuxiangmen, Shangwumen, Anyuanmen, Shangdemen, Jiefangmen, Shangjianmen, Shangqinmen, Chaoyangmen, Zhongshanmen, Changlemen, Jianguomen, Peace Gate, Wenchangmen. The 18 gates have different formation times and specifications.[7] Xi'an city wall is the first key cultural relics protection unit in China. At the same time, Xi'an City Wall, Beilin Historical and Cultural Scenic Area and Xi'an Moat have been awarded the title of National 5A-level tourist scenic spot and "National Water Conservancy Scenic Area" respectively.[3