The Longmen Grottoes are located in the south of Luolong District of Luoyang. Here two mountain cliffs stand face to face, like a pair of natural watchtowers over the Yi River that flow between them, giving rise to the name “Luoyang’s Yi River Watchtower Gate.”
2006, “Cultural Relics”, in 王琴 [Wang Qin], 韩清月 [Han Qingyue], 冯鑫 [Feng Xin], transl., edited by 杨长春 [Yang Changchun], 河南:文化大中原 [Henan: The Central Plains of Chinese Culture] (全景中国 [Panoramic China]), 1st edition, Beijing: Foreign Languages Press, page 163