西安现存的明代城墙,系隋、唐京城中皇城改造与扩建而成,并经明清两代不断修葺完善的。长乐门城楼位于西安城墙东部偏南,明洪武三年至十一年(1370—1378),利用“奉元城”(唐末新城)旧址,将城的北墙和东墙平行向外扩展约三分之一,设四门,东门即长乐门。 The existing Ming Dynasty city wall in Xi’an is the transformation and expansion of the imperial city in Sui and Tang dynasties. It was repaired by the Ming and Qing dynasties. The Changle Gate Watchtower is located in the south of the eastern part of Xi’an City Wall. From Mingwu three years to eleven years (1370-1378), using the site of “Feng Yuan City” (Tang Dynasty New Town), the north wall and east wall of the city are extended outward by about One-third, set four, the east gate is the long door.