蓟门烟树——“蓟门烟树”一词最早见于唐代诗人李益的七绝诗:“惆怅秦城送独归,蓟门烟树远依依。秋空莫射南来雁,纵遗乘风更北飞。”乾隆皇帝寻访古迹,指元大都西墙残门为蓟门。其实,历史上的蓟门不在元大都西城墙北部,根据考证,其地大约在今宣武门外大街西侧一带。据史料和乾隆的诗,后在学院路西 Thistle door tobacco - “Thistle door tobacco tree” was first seen in the Tang Dynasty poet Li Yi’s seven-poem: “Melancholy Qincheng get home alone, Pilgrimage wind more north fly. ”Emperor Qianlong to visit monuments, referring to the majority of the western wall of the door for the Jimen door. In fact, the history of Jimen is not located in the north of Xidaduchengchengcheng, according to textual research, to the west of Xuanwumen Street about this area. According to the historical data and Qianlong’s poem, after the College Road West