Due to my recent walk here a short notice about Yangfangkou Great Wall:
This is by far the best proctected GW I have ever seen. The remaining Wall is at least 10m high. Much more prominent than that is the fact that the beacon towers are of a total unique kind: not of (about) quadratic footprint but very elongated. Roughly about 6m broad on top and about 15m long. The function is clear: The wall should be in reach of bowmen standing on top of these towers. The towers are in a distance of about 150m, the secend best protected section I know (Ningxia, Xiaolongtou) hast towers in distances of average 200m. Also prominente are small fortresses along the GW at Yangfangkou. The impression is that the people who built the wall here were in great fear of something ...
The wall is snaking onto the top of the surrounding mountains (up to roughly 2000m), it will be worth to walk up there in a slightly warmer season. Since there are no villages up there it will be neccessary to sleep outdoors.
Here some impressions:
A beacon tower of the Hebei-Style
The wall running up the mountain
The elongated type of towers (or even wall sections)
-chinoook