Richat Structure - The Eye of Africa

By Google Maps - Imagery (c) TerraMetrics

The Richat Structure, or the Eye of Africa, as it’s also called, is a huge geological formation 50 kilometers across. Smack dab in the middle of the Sahara Desert in Mauritania, this feature that looks remarkably like an eye was immediately noted by the very first astronauts, as it is glaringly obvious in the otherwise rather featureless Sahara.