"They were built around 1960's to 1970's, by Grand General Lin Biao, the chief of Chinese Millitary back then. The main purpose is to defend a possible Russian invasion. There are totally nine of them, each of which has adequate firearm and sufficient water supply. These constructions were abandoned in late 1970's and now some of them are developed into resorts."
These half mile long moats each surround a 1000 foot long mound in the center. There are moats 12 miles north
and one that seems to be overgrown 12 miles south
A large spaceport is to the south where China launched it's first manned space mission. The area to the west looks like China's version of Edwards AFB.