https://www.chinahighlights.com/greatwall/section/overhanging-greatwall.htm
The Overhanging Great Wall in Jiayuguan, Gansu Province
Jiayuguan Overhanging Great Wall was an integral part of the ancient defense system at the Jiayuguan Pass, made of graves and yellow earth by tamping.
great walljiayuguan gansuoverhangingprovince