Looking closely at the soil/vegetation disturbances in the area around the structures in pic 4. Large numbers of areas that look to have been scraped/dug or mown within the last 6 months to a year. Look for the irregularly curved parallel ridges, in particular.
The tightly grouped long roofed structures could be living/office structures. Could this be a prison or detention facility?
Anybody else think the parallel straight rows of dark flat objects are solar panels?
I don't even have a guess at the purpose for those round cornered rectangular shapes in the semicircle.