14 Mysterious Landmarks That Science Still Can't Fully Explain

5. The Richat Structure ("Eye of the Sahara," Mauritania): Geological Enigma

Visible even from space, the Richat Structure in Mauritania is a colossal, near-perfectly circular geological formation spanning 30 miles in diameter. Initially believed to be an impact crater, closer examination reveals it's a deeply eroded dome, but its precise, concentric rings and circularity are still debated. How natural erosion sculpted such an astonishingly symmetrical "eye" is a perplexing question. Its sheer scale and uncanny resemblance to an iris have even fueled speculative theories about it being a remnant of the mythical city of Atlantis, further deepening its scientific allure.