FADED WHEELS
In Northeast Africa there are structures that look like wheels and were probably settlement sites for earlier inhabitants. They look strikingly similar to the ancient "wheels" in Jordan. However, they stand out much weaker from the ground here and are sometimes hardly recognizable. 
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Images courtesy of Google Earth™
With these images, however, it must be borne in mind that the age of the structures cannot be assessed from the air. Whether such a circle has existed for thousands of years or was created by a shepherd only a few decades ago as a fence for his animals and then abandoned again can hardly be distinguished on satellite images. Only precise investigations on the ground could clarify which of these structures are really old and which are possibly more recent.
These pictures are only a small selection. All objects I found are included in the following download (Google Earth required): Download Google Earth placemarks >