The Gaotai/Hei he Great wall is not easy to find. It is manly coverd by sand dunes (hard to walk on) and shows only at very few stretches, lying signigicantly below the surrounding sand level.
There are some beacon towers around and along the Great Wall which are easy to find.
This tower in my nomenclature corresponds to the term "Monster". Its debris is scattered over a circle of about 40m and the trunk still standing is one if not the biggest Great Wall tower I have ever seen (which means among thousands ...).
A Great Wall section vanishing beneath sand dunes:

-chinoook