Nabta Playa was once a large basin in the Nubian Desert, located approximately 800 kilometers south of modern day Cairo or about 100 kilometers west of Abu Simbel in southern Egypt, 22° 32' north, 30° 42' east. Today the region is characterized by numerous archaeological sites.
Read more about Nabta Playa: Early History, High Level of Organization, Religious Ties To Ancient Egypt, One of The World's Earliest Known Examples of Archeoastronomy