This mysterious fortress in china, known as Hejin City Fortress, is extremely difficult to see from a distance, blending smoothly with the surrounding terrain and making it a perfect hideaway. Even the locals have little knowledge of its historical origin. The fortress’s meaning and design were uncovered only thanks to the knowledge of an 80-year-old resident named Hou Jun’e. | Unsolved Mysteries & Paranormal Activities

This mysterious circular island in Argentina not only floats, but also rotates constantly - and we don’t really know why. “The Eye” or “El Ojo,” located in the Paraná Delta, Argentina, is about 120 meters across and rotates on its own axis. Despite scientific research and even speculation about UFOs, its origin remains a mystery. | Unsolved Mysteries & Paranormal Activities