10. Pharaoh's Secret Tunnel Explored
Standing on wooden steps that protect a 3,300-year-old stone staircase, Egyptian antiquities chief Zahi Hawass poses in 2009 in a mysterious tunnel that links the ancient tomb of Pharaoh Seti I to ... nothing.
After three years of hauling out rubble and artifacts via a railway-car system (rails visible at left), the excavators hit a wall, the team announced in July. It seems the ancient workers who created the steep tunnel under Egypt's Valley of the Kings near Luxor (map) abruptly stopped after cutting 572 feet (174 meters) into rock.