Roden Crater is an extinct volcano crater near Flagstaff, Arizona (U.S.). Artist James Turrell purchased the 400.000 year old, 3km wide crater in 1979 and has been transforming it into into a massive naked-eye observatory, designed specifically for the viewing of celestial phenomena. Mr. Turrell has moved tons of earth to carve out different kinds of viewing chambers and tunnels — making his art of light, sky and astronomical events. Writers have compared it to Stonehenge and the Mexican pyramids. He plans to open the crater for public viewing in 2011.