Introduction to the Seventy-Two Coupon Tower: Located on the Great Wall on the top of the south side of Qingshan Pass, it is also called the "Water God Tower" by the locals. It was built by Qi Jiguang, the chief military officer of Ji Town in the Ming Dynasty. The windows, doors, ladders, observation holes, structural walls and "closets" inside the building, and the sentry room on the roof of this building total 72 arches, hence the name.