Nine-Eyes Tower sits on one of the mountains peaks that surround the Jiankou area. It's named 'Nine-Eyes Tower' because, when it was in original condition, each of the walls of the lower levels had nine big windows.
After walking into and out of two valleys, we took a steep climb up wall built on a ridgeline, reaching the Nine-Eyes Tower just in time for lunch. The weather was reasonably clear, and we could see much of the Great Wall in the area, including the Chinese Knot. From the tower, we followed a hill trail that led us in a loop back to the wall, passing the remains of an old walled barracks on the way.
Once back to the wall, we followed it towards the Chinese Knot, passing through and around quite a few towers. On the way up to the Chinese Knot, the wall becomes near-vertical - just before that point we climbed down off the wall, and followed a hill trail down to the village where our bus was waiting for us, and enjoyed snacks and drinks before heading back to the city.
Statistics: Approx. 5 hours in total, with 3.5 hours of walking over 8km; start height 584m, finish height 629m, highest point 1193m (Nine-Eyes Tower). Estimated 1578kCal burned.