Whilst this is slightly out of what there is on TMA its fascinating to read about this particular stone circle, its presumed astronomy, (on four opposing stones?) and the fact that there seems to be cow burials as well....

http://www.mnsu.edu/emuseum/archaeology/sites/africa/nabtaplaya.html

"Another major feature at Nabta is a group of thirty “complex structures.” These structures are located about a kilometer south of the cattle tumuli measuring 500 meters in length and 200 meters in width. The framework was constructed by using roughly shaped or unshaped stones that were set upright to form a structure that was oval in shape measuring 5 meters by 4 meters. Aside from a few minor details, all of the structures were basically the same. They all face slightly west of north and they all have one or two large stone slabs that lay horizontally in the center of the structure. What makes them unique is that they have been built over large mushroom-shaped tablerocks. The tablerocks were shaped by years and years of erosion and then covered by two to three and a half meters of playa clays and silts."........

pictures here... http://iconoclastreport.com/news/hidden-hist/126

Not of course as old as the Gobekli Tepe stone circle, but interesting nevertheless.....