长安可能是中国历史上最著名的都城。它的影响所及,导致日后的明清人也往往在诗作里用“长安”来指代北京城。选择长安为都城的理由很多,最明显的一个理由是它的地理位置。就军事关塞而言,长安周边东有潼关,西有大散关,南有武关,北有萧关,四座关口控制着进出长安的通道,都是易守难攻。就地理而言,长安有一个安全的地形。当然,洛阳在唐朝中后期的崛起也有赖于它四通八达的交通优 Changan may be the most famous capital in Chinese history. Its influence has led to the Ming and Qing dynasties in the future often use “Changan” in the poem to refer to Beijing. There are many reasons for choosing Chang’an as the capital city. One of the most obvious reasons for this is its geographical location. As far as military traffic congestion is concerned, there are Tongguan in the east of Chang’an, the bulk of the pass in the west, the Wu Guan in the south, the Xiao Guan in the north, and the four gates that control access to Chang’an. Geographically, Changan has a safe terrain. Of course, the rise of Luoyang in the middle and late Tang dynasty also depends on its ease of transportation in all directions