I believe the Great Hall of Records was Found.

[guohua]

Thanks @"guohua" !

You might be surprised to learn my curiosity about this area of China was prompted by Louis L'Armour . . . not well known that he wrote more than just fiction about the Old West of the USA.

Cheers

My husband says he knows of Louis Armour  but I do not.

Out in the Gobi Desert and other mountainous regions you'll find No Fly Zones with the PLAAF (People's Liberation Army Air Force) responding to radar tracking sites.
With the foliage and ground penetrating equipment that can be used from aircraft today, I think they stay busy.
I understand (from years ago) when I was privy to some information, that these sites are very large.
Tourist are warned not to approach these sites, many have gone missing and they blame the deaths on the desert.