"The Eye of the Sahara", also known as the "Richtat Structure", is located in Mauritania, Africa.

Some believe it was the location of "Atlantis".
(2 Pictures below)

Plato (428-347 BC), Athenian Philosopher of the Classical period, believed that as the Atlanteans of Antlantis grew powerful through conquest; their ethics declined. Later, by way of divine punishment, the island was beset by earthquakes and floods, only to sink into a muddy sea.

Pictured below is artwork based off of Plato's own description of Atlantis.
(2 pictures)