Roden Crater is a cinder cone type of volcanic cone from an extinct volcano, with a remaining interior volcanic crater. It is located northeast of the city of Flagstaff in northern Arizona, United States. The artist James Turrell, for his land art project, acquired the 400,000-year-old, 3-mile-wide (4.8 km) crater's land. Turrell has since been transforming the inner cone of the crater into a massive naked-eye observatory, designed specifically for the viewing and experiencing sky-light, solar, and celestial phenomena. The fleeting Winter and Summer solstice events will be highlighted. The Dia Art Foundation is continuing to advocate for the development of James Turrell's Roden Crater project in the Painted Desert in Arizona which was begun in the 1970s with Dia's support. James Turrell, who purchased the Roden Crater in 1979, had plans to open the crater for public viewing in 2011.