Nabta Playa was once a large basin in the Nubian Desert . It is about 500 miles south of modern day Cairo or about 100 kilometers west of Abu Simbel of southern Egypt , 22 Â 32 ' north , 30 Â 42 ' east . 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 Â 32 ' north , 30 Â 42 ' east .