North Africa, Sahara Dessert, Mauritania. The bizarre feature is known as the Eye of the Sahara.
The eye of the Sahara also known as the Richat Structure or Guelb er Richat, is a highly unusual and some might venture to say - bizarre circular formation in the Sahara desert. This structures origins are uncertain, but it dates far into uncharted antiquity.
Its 40 mile wide dome is heavily eroded. It's construction , either by natural phenomena or intelligent design has exposed sedimentary rock from Late Proterozoic era, which is the time immediately preceding the proliferation of complex life on Earth - roughly 2.5 Billion years ago give or take a few hundred Centuries. The interior of the eye of the Sahara contains various igneous and volcanic rocks.
Natural or Man Made Formation
Initially it was believed to have been created by an asteroid impact. It is now believed to be a bizarrely circular symmetrical and deeply eroded geologic dome. There is zero evidence for shock metamorphism which would indicate a meteor impact.
Some believe the structure may have been created by intelligent design, be it Human or an alien intelligence, however the consensus seems to be that it is hydro-thermal alteration, dissolution and collapse of the unique collection of varying rock structure accumulated within the structure over the eons.