The Richat Structre is a very unusual circular geological formation, 30 miles in diameter, located in the Sahara Desert in the country of Mauritania. Because of its circular structure with rings visible from space, it has been called the "Eye of the Earth", "Eye of Africa", and various other names. The cause and origin of this formation is a mystery.
Sources of Infromation:
1. Wikipedia: http://en.wikipedia.org/wiki/Richat_Structure
2. Anonymous. "Which Planet Has a 30-Mile-Wide Eye?" ID (Ideas and Discoveries) (ISSN:2161-2641), Vol. , No. (March, 2014), page 54; This one page article has a large photo of the Richet Structure.