The discovery of a once-hidden, sealed-off corridor inside of one of Egypt's Pyramids of Giza was revealed to the public on Thursday, a development that could spark future findings inside one of the ancient Seven Wonders of the World. The corridor, which measures nearly 30 feet long and over 6 feet wide, is located in the 4,500-year-old Pyramid of Khufu's north side, near its main entrance, Egyptian authorities said. The cavity was first observed by the Scan Pyramids team in 2016, among other discoveries, through "cosmic-ray muon radiography that is a non-destructive technique ideal for the investigation of large-scale structures." Click the link in our bio to learn more.